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INTRODUCTION! 
TO    BOTANY 


UNIVERSITY    OF    CALIFORNIA 


DEPARTMENT  OF  EDUCATION 


GIFT  OF  THE   PUBLISHER 


No. 


Vetoed       /   ?  0  3  , 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

GIFT    OF 


BIOLOGY 
LIBRARY 

G 


Class 


INTRODUCTION    TO 
BOTANY 


BY 


WILLIAM    CHASE   STEVENS 

\\ 

PROFESSOR   OF   BOTANY   IN   THE   UNIVERSITY   OF   KANSAS 


BOSTON,   U.S.A. 

D.   C.   HEATH   &   CO.,    PUBLISHERS 
1902 


BIOLOGY 

LIBRARY 

G 


COPYRIGHT,   1902, 
BY  D.  C.  HEATH  &  Co. 


PRINTED   IN 

UNITED    STATES 

OF    AMERICA 


PREFACE. 

ENOUGH  work  has  been  outlined  in  this  book  for  a  year's 
course  in  those  schools  that  are  prepared,  by  suitable  time 
allotted  to  the  subject  and  by  laboratory  equipment,  to 
do  comprehensive  and  thorough  work.  A  term  could  be 
devoted  to  the  work  outlined  in  Chapters  I  to  X  inclusive ; 
and  where  the  daily  laboratory  periods  are  one  hour  or 
less,  the  entire  school  year  could  be  profitably  occupied 
by  the  course  there  outlined.  It  is,  of  course,  presumed 
that  the  teacher  will  select  from  the  book  such  work  as 
the  possibilities  of  his  school  warrant.  It  is  not  expected 
that  each  student  will  perform  all  of  the  physiological 
experiments  herein  outlined ;  but  different  experiments 
are  to  be  assigned  to  individuals  or  groups  of  students, 
the  results  to  be  used  for  purpose  of  demonstration  before 
the  entire  class. 

Much  stress  is  laid  on  laboratory  work,  which  is  to  be 
done  with  the  utmost  possible  care  and  accuracy,  not 
only  that  the  student  may  respect  his  work  and  that  the 
knowledge  gained  may  be  exact,  but  also  that  the  fine 
opportunity  which  the  study  of  plants  so  richly  affords 
for  training  in  seeing  and  interpreting  facts,  may  not  be 
passed  by. 

In  the  discussion  following  each  set  of  laboratory  direc- 
tions it  is  inevitable  that  results  which  the  student  is 
expected  to  work  out  for  himself  are  sometimes  told ;  but 

22lf46 


iv  Preface. 

there  is  a  large  body  of  work  for  which  no  such  aid  is 
given,  quite  sufficient  for  training  in  independent  and 
self-reliant  study. 

In  order  that  the  student  may  not  be  hampered  with 
preconceptions  of  what  he  is  expected  to  see  and  to  repre- 
sent, in  choosing  the  illustrations  care  has  been  exercised 
to  avoid  in  most  instances  those  subjects  which  he  is 
required  to  *  draw  in  his  laboratory  book.  And  that  the 
main  facts  about  the  nature  of  plants  may  be  kept  plainly 
before  the  student,  glossology  has  for  the  most  part  been 
kept  from  the  discussions  and  placed  in  compact  form  in 
Part  III. 

I  wish  to  acknowledge  my  special  indebtedness  to  my 
colleague,  Professor  M.  A.  Barber,  in  conjunction  with 
whom  a  large  part  of  the  course  here  outlined  has  been 
worked  out.  He  has  read  most  of  the  manuscript  and 
has  made  many  helpful  suggestions. 

The  manuscript  has  been  examined  by  Dr.  C.  E.  Mc- 
Clung,  Associate  Professor  of  Zoology,  University  of 
Kansas;  Dr.  V.  M.  Spalding,  Professor  of  Botany,  Uni- 
versity of  Michigan;  Dr.  John  W.  Harshberger,  Instructor 
in  Botany,  University  of  Pennsylvania;  Dr.  Rodney  H. 
True,  Plant  Physiologist,  Department  of  Agriculture, 
Washington,  D.C. ;  Mr.  L.  Murbach,  Central  High  School, 
Detroit,  Michigan;  Principal  Maurice  Ricker,  High  School, 
Burlington,  Iowa. 

The  proof  has  been  read  by  Dr.  D.  M.  Mottier,  Pro- 
fessor of  Botany,  University  of  Indiana;  Dr.  Charles  H. 
Clark,  Phillips  Academy,  Exeter,  New  Hampshire ;  Dr. 
F.  C.  Newcombe,  Junior  Professor  of  Botany,  University 
of  Michigan ;  B.  M.  Stigall,  Instructor  in  Biology,  Manual 
Training  High  School,  Kansas  City,  Missouri. 

Dr.   E.   C.  Franklin,  Professor  of   Physical  Chemistry, 


Preface.  v 

University  of  Kansas,  has  revised  the  paragraphs  dealing 
with  the  nature  of  diffusion  and  osmosis.  Dr.  S.  W.  Wil- 
liston,  Professor  of  Paleontology,  University  of  Chicago, 
has  read  the  chapter  on  Plants  of  Past  Ages  ;  S.  J.  Hunter, 
Associate  Professor  of  Comparative  Zoology,  University 
of  Kansas,  has  read  those  portions  of  Chapter  VIII  deal- 
ing with  the  anatomy  of  insects;  M.  W.  Sterling,  Associate 
Professor  of  Greek,  University  of  Kansas,  has  revised  and 
contributed  to  the  etymology  of  terms  in  the  glossary  and 
flora;  Dr.  W.  H.  Carruth,  Professor  of  German,  Univer- 
sity of  Kansas,  has  revised  the  passages  translated  from 
Sprengel. 

To  all  of  these  teachers  I  wish  to  express  my  grateful 
sense  of  obligation  for  suggestions  leading  to  the  better- 
ment of  the  book. 

The  illustrations  have  been  made  by  Miss  Marguerite 
Wise,  Instructor  in  Botany  and  Zoology,  University  of 
Kansas,  Mr.  Sidney  Prentice,  Miss  Luella  Pugh,  and  Miss 
Katherine  Crew.  I  wish  to  acknowledge  my  special  in- 
debtedness to  Miss  Wise,  whose  knowledge  of  the  subject 
has  greatly  lightened  the  task  of  preparing  the  illustra- 
tions. She  has  made  all  of  the  wash  drawings  excepting 
Fig.  192,  which  is  by  Miss  Crew.  Of  the  original  line 
drawings,  Mr.  Prentice  made  Figs.  10,  19,  21,  37,  45,  47, 
48,  93,  1 80,  198,  199,  201,  202,  203,  204.  The  remainder 
of  the  original  illustrations  and  most  of  the  copied  figures 
were  done  by  Miss  Wise. 

W.  C.  S. 

UNIVERSITY  OF  KANSAS. 


CONTENTS. 

PART   I. 
MORPHOLOGY,   PHYSIOLOGY,   AND    ECOLOGY. 

CHAPTER  PAGE 

I.  LABORATORY  WORK i 

II.  SEEDS  AND  SEEDLINGS 5 

III.  ROOTS 28 

—  IV.  BUDS  AND  STEMS    .    .    .    .       .    -  45 

V.  LEAVES 75 

VI.  GROWTH  AND  MOVEMENT 100 

VII.  MODIFIED  PARTS 134 

VIII.  FLOWERS 147 

IX.  DISPERSION  OF  FRUITS  AND  SEEDS     ....  207 

X.  STUDIES  OF  SELECTED  SPERMATOPHYTES    .        .        .218 

XI.  SLIME  MOULDS,  BACTERIA,  AND  YEASTS    .        .        .251 

XII.  ALG.E,  FUNGI,  AND  LICHENS 264 

XIII.  MOSSES,  FERNS,  AND  HORSETAILS       ....  286 

XIV.  ADAPTATION  TO  ENVIRONMENT    .         .         .        .        .  303 
XV.  PLANTS  OF  DIFFERENT  REGIONS         .        .        .        .328 

XVI.  PLANTS  OF  PAST  AGES 351 

XVII.  CLASSIFICATION  OF  PLANTS         .  359 


viii  Contents. 


PART    II. 

THE   HERBARIUM,   LABORATORY   EQUIPMENT, 
AND  PROCESSES. 

CHAPTER  PAGE 

XVIII.    THE  SCHOOL  HERBARIUM    .        .        .  .        .    367 

XIX.     LABORATORY  EQUIPMENT 371 

XX.     REAGENTS  AND  PROCESSES 381 


PART    III. 

GLOSSOLOGY. 
GLOSSARY 399 


INDEX  TO  PARTS  I  AND  II 429 


INTRODUCTION   TO    BOTANY. 


CHAPTER   I. 
LABORATORY  WORK. 

1.  Method  of  Study.  — The  study  of  plants,  to  be  of  much 
value,  requires  accurate  observation.  This  is  best  secured 
by  a  definite  and  orderly  record,  by  the  student,  of  what 
he  has  seen.  Simple  drawings  are  usually  more  effective 
than  a  verbal  description,  and  are  therefore  much  used 
;r  fV>e  work  here  outlined.  Students  unskilled  in  drawing 
ne°,t  rot  be  discouraged  by  this  requirement,  for  after 
som<:  nn)0  of  persistent  and  patient  effort  the  number  of 
thuse  who  cannot  achieve  passably  good  results  is  few 
indeed.  The  drawings  furnish  the  best  possible  mode  of 
expression  in  the  study  of  form  and  structure,  for  they  show 
briefly  and  positi  ely  how  well  the  student  has  observed. 

It  is  best,  as  a  rule,  not  to  point  out  the  faults  of  the  draw- 
ings to  the  studer^-  but  to  have  him  detect  them,  which  he 
rarely  fails  to  b.  ole  to  do  when  asked  where  the  faults 
lie.  The  drawin  ,  should  be  very  simple,  but  never  merely 
sketchy.  Every  line  should  have  a  meaning  and  should 
clearly  indicate  what  it  is  intended  to  show.  Only  outlines 
are  desired  ;  shading  is  unnecessary,  and  should  not  be 
attempted  except  by  one  who  thoroughly  understands  its 
application.  :  : 


2  Introduction  to   Botany. 

There  are  three  simple  rules  which  the  student  should 
keep  in  mind,  (i)  The  drawings  should  be  on  a  suffi- 
ciently large  scale  to  allow  the  smallest  details  to  be  put  in 
without  crowding.  (2)  All  parts  must  be  in  correct  pro- 
portion with  reference  to  one  another  and  in  right  relative 
positions.  (3)  Some  one  dimension  of  the  object  should 
always  be  used  as  a  measuring  rod  in  establishing  the 
lengths  of  the  others.  If  these  rules  are  followed,  much 
subsequent  correction  will  be  avoided.  A  very  serviceable 
notebook  for  the  notes  and  drawings  is  afforded  by  the 
No.  2  double  and  reversible  note  covers,  opening  at  the 
side,  filled  with  a  good  quality  of  unruled  linen  ledger 
paper.1 

The  drawings  should  be  symmetrically  disposed  over 
the  sheet  without  crowding,  as  shown  in  Fig.  74.  They 
should  be  made  with  a  6  H  drawing  pencil  kept  quite 
sharp  by  rubbing  it  occasionally  with  a  longitudinal  to-and- 
fro  motion  on  a  piece  of  No.  o  emery  cloth  or  sandpaper. 
Neither  a  soft  nor  a  dull  pencil  should  ever  be  used.  The 
descriptive  notes,  written  in  ink,  should  be  on  a  separate 
sheet  facing  the  drawings,  the  parts  of  which  are  to  be 
lettered  and  referred  to  in  the  notes  accordingly.  Notes 
written  with  a  pencil  are  liable  to  smirch  the  drawings  and 
must  not  be  tolerated.  The  student  should  strive  for  the 
utmost  accuracy  and  neatness  in  the  drawings  and  notes  ; 
he  should  have  a  personal  pride  in  them,  for  they  repre- 
sent his  capabilities  in  seeing  and  interpreting  facts  with 
which  he  has  personally  to  deal. 

2.  Procedure  in  Drawing.  — After  having  determined  the 
proper  scale  of  the  drawing,  that  is,  whether  its  diameters 
should  be  twice  as  great,  three  times  as  great,  etc.,  as  those 
of  the  object,  place  points  to  establish  the  limits  of  the 

1  Made  by.(?h^3f  W.  Sever  &:Cp.,:  Cambridge,  Mass. 


Laboratory  Work.  3 

long  and  short  diameters,  using  the  short  diameter,  for 
instance,  as  a  measuring  rod  ;  and  then  with  a  very  light 
touch  of  the  pencil,  making  a  barely  visible  line,  draw  the 
outline.  If  the  form  is  not  right  at  the  first  attempt,  correct 
it  before  rubbing  out  the  false  line,  for  the  latter  may  serve 
as  a  guide  in  correcting  the  error.  When  the  form  has 
been  satisfactorily  drawn,  rub  out  the  false  lines  once  for 
all,  and  retrace  the  final  outline  with  a  firm  touch  so  that 
it  stands  out  sharply,  but  the  pressure  of  the  pencil  must 
not  be  hard  enough  to  dig  into  the  paper. 

Colored  pencils  are  very  helpful  for  giving  distinct  tints 
to  the  different  parts  of  a  drawing,  but  they  should  be  used 
only  where  a  definite  purpose  is  to  be  served,  as  in  calling 
attention  to  homologous  parts  in  different  drawings.  The 
coloring  should  be  done  with  very  light  cross-hatching 
strokes  until  an  even  light  tint  is  produced.  If  satisfactory 
results  are  not  obtained  in  this  way,  the  color  can  be  dis- 
tributed more  evenly  by  rubbing  over  the  colored  areas 
with  a  paper  or  chamois  stump  used  by  artists  in  crayon 
shading. 

3.  The  Student  at  Work.  — The  student  should  think  of 
his  work  as  he  proceeds.  The  drawings  and  notes  are  in- 
tended to  assist  him  in  gaining  a  clear  conception  of  the 
problems  before  him,  and  they  are  good  evidence  of  his 
success  or  failure ;  but  he  should  possess  his  subject  more 
completely  than  the  drawings  and  notes  may  show.  The 
laboratory  is  so  much  limited  space  in  which  certain  con- 
veniences for  work  are  provided.  Were  it  not  for  these 
conveniences,  it  would  be  better  to  study  the  subjects  out 
of  doors  in  their  natural  surroundings.  The  student  who 
thinks  as  he  works  associates  the  subject  with  the  natural 
conditions,  and  sees  the  bearing  of  what  he  is  learning  in 
the  laboratory  on  the  life  of  plants  as  they  occur  in  nature. 


4  Introduction  to  Botany. 

The  student  should  never  ask  the  teacher  questions 
which  with  reasonable  effort  he  can  answer  for  himself ; 
as  questions  arise,  he  should  continually  recur  to  the  sub- 
ject of  his  study  as  the  most  reliable  source  of  information 
about  itself. 

It  is  a  good  plan,  when  pertinent  questions  are  asked, 
to  write  them  on  the  blackboard  for  the  class  to  consider, 
and  finally  to  use  them  as  topics  for  a  general  discussion. 

4.  Field  Work.  —  The  laboratory  work  should,  of  course, 
be  supplemented  by  field  work.  The  locality  where  the 
work  is  to  be  carried  on  should  first  be  visited  in  order  to 
determine  what  the  students  can  best  learn  there ;  then 
questions  and  directions  should  be  written  on  the  black- 
board for  the  student  to  copy,  in  order  that  his  work  may 
have  definiteness  and  meaning.  Drawings  and  notes 
which  are  to  count  as  an  essential  part  of  the  course 
should  be  required  in  this  work.  In  succeeding  chapters, 
problems  are  given  which  are  to  be  worked  out  in  the  field, 
but  they  will  need  to  be  supplemented  by  others  particu- 
larly adapted  to  the  specific  locality. 


CHAPTER   II. 
SEEDS  AND  SEEDLINGS. 

PROVIDING   MATERIALS. 

It  is  a  simple  matter  to  provide  the  seeds  required  for  the  work  of 
this  chapter,  but  there  may  be  some  difficulty  in  growing  the  seedlings 
on  account  of  lack  of  space  and  equipment.  If  a  greenhouse  cannot  be 
used,  some  arrangement  must  be  made  for  growing  the  seedlings  in  a 
warm  room.  Boxes  should  be  made  not  more  than  six  inches  deep, 
and  white  pine  sawdust,  or  chopped  sphagnum  when  obtainable,  should 
be  placed  in  these  to  a  depth  of  four  inches.  If  the  classes  are  large 
and  the  space  which  can  be  devoted  to  seed  boxes  very  limited,  they 
may  be  placed  one  above  another  in  tiers  separated  by  a  space  of  about 
ten  inches.  Moisten  the  sawdust  throughout  and  then  plant  the  seeds 
to  a  depth  of  about  one  inch  in  rows  between  two  and  three  inches 
apart.  After  covering  the  seeds,  press  the  sawdust  down  firmly  with 
the  palm  of  the  hand  or  with  a  wooden  block.  The  seeds  will  germi- 
nate more  quickly  if  soaked  in  water  over  night  before  planting.  The 
first  sowings  should  be  made  about  two  weeks  before  the  work  is  to 
begin,  and  then  other  sowings  of  the  same  kinds  of  seeds  at  intervals 
of  a  few  days,  in  order  that  plenty  of  seedlings  may  be  on  hand  in  dif- 
ferent stages  of  germination.  The  seeds  need  to  be  kept  warn,!  and 
well  watered,  but  it  is  not  necessary  that  they  should  have  light  until 
they  have  germinated ;  after  that  time  the  seedlings  will  grow  weak 
and  spindling  if  too  much  shaded. 

OBSERVATIONS  ON   SEEDS  AND   SEEDLINGS. 

Lima  Bean. 

i.  Make  drawings  of  the  external  appearance  of  a  dry 
bean  from  the  two  most  important  points  of  view,  showing 
all  structural  characteristics.  Make  drawings  to  the  scale, 

5 


6  Introduction  to  Botany. 

x  1.5  ;  that  is,  the  diameters  of  the  drawings  are  to  be  1.5 
times  as  great  as  the  corresponding  diameters  of  the  bean. 
The  two  most  important  points  of  view  are  those  which 
best  show  the  form  of  the  bean,  and  the  structures  which 
may  have  some  significance  in  the  formation  or  germina- 
tion of  the  seed.  If  beans  in  the  pod,  preserved  in  2% 
formalin,  or  in  70%  alcohol,  are  available,  the  data  for 
judgment  will  be  more  complete.  Compare  with  the  dry 
bean  one  which  has  been  soaked  in  water  over  night,  and 
note  any  difference  in  size,  form,  and  texture. 

2.  Slip  the  skin  or  seed-coats  (there   are  usually  two 
seed-coats,  the  outer,  termed  the  testa,  being  thicker  and 
harder  than  the  inner)  carefully  from  a  soaked  seed,  notic- 
ing whether  it  is  attached  to  the  rest  of  the  seed  at  any 
point,  or  simply  lies  in  contact  with  it.     Can  any  structures 
be  seen  after  the  seed-coats  are  removed  which  could  not 
be  seen  before  ?     If  so,  make  drawings  from  the  two  points 
of  view  which  will  most  clearly  show  them.     Is  there  any 
connection  between  structures  which  are  removed  with  the 
seed-coats  and  those  lying  beneath  them  ?     How  do  the  dry 
and  soaked  seed-coats  of  the  bean  differ  as  to  hardness 
and  toughness  ?    What  significance  do  you  see  in  the  differ- 
ence ?     In  what  ways  is  the  seed  protected  against  injury  ? 
Answer  these  questions  in  the  notes,  and  refer  to  the  draw- 
ings wherever  they  will  illustrate  what  is  said. 

3.  After  the  seed-coats  have  been  removed,  note  whether 
the  two  halves  of  the  bean,  termed  cotyledons,  are  united 
at  any  point;  then  carefully  separate  the  cotyledons  and 
place  them  on  the  table,  convex  side  down,  and  in  contact, 
at  the  right  point,  with  any  part  from  which  they  may 
have  been  severed.     Draw  as  thus  seen  on  the  same  scale 
as  before. 

4.  Study  with  a  lens  the  structures  which  were  revealed 


Seeds  and  Seedlings.  7 

by  separating  the  cotyledons,  and  draw  to  a  scale  suffi- 
ciently large  to  bring  out  the  details  thus  observed,  say, 
x  4.  If  any  parts  are  folded  together,  make  drawings  to 
show  their  relationship  clearly.  The  student  should  not 
be  satisfied  with  his  work  until  the  drawings  show  the  facts 
as  clearly  as  he  can  see  them  by  a  thoughtful  examination 
of  the  object. 

Germinating  Lima  Bean. 

5.  Make  drawings  of  a  bean  in  the  first  stages  of  germi- 
nation, and  in  various  succeeding  stages,  identifying  the 
parts  already  studied   in  the  ungerminated  seeds.     Note 
any  new  structures. 

6.  The  following  terms  should  now  be  applied  in  the 
notes  to  the  structures  designated  by  them :  — 

The  scar  where  the  seed  was  attached  to  the  pod  is 
called  the  hilum. 

The  rudimentary  plant  formed  in  the  seed  is  called  the 
embryo. 

The  first  leaves  of  the  embryo  are  called  the  cotyle- 
dons. 

The  bud  sometimes  present  between  the  cotyledons  is 
called  the  plumule. 

The  small  stem  in  the  seed  from  which  the  cotyledons 
grow  is  called  the  caulicle. 

The  first  root  produced  as  a  continuation  of  the  caulicle 
is  called  the  radicle. 

All  of  the  embryo  below  the  insertion  of  the  cotyledons 
is  called  the  hypocotyl  (including  caulicle  and  radicle). 
All  of  the  embryo  above  the  insertion  of  the  cotyledons  is 
called  the  epicotyl. 

The  opening  in  the  seed-coats  near  the  tip  of  the  caulicle 
is  called  the  micropyle. 


8  Introduction  to  Botany. 

7.  After  the  drawings  have  been  pronounced  satisfactory 
by  the  instructor,  impart  different   tints   to  the   separate 
structures  by  means  of  colored    pencils,  using   the   same 
colors  for  the  corresponding  parts  in  the  germinated  and 
ungerminated  seeds.     Thus  :  color  the  cotyledons  yellow, 
the  plumule  and  whatever  develops  from  it  green,  the  cau- 
licle  orange,  the  radicle  and  succeeding  roots  red,  reserve 
food  outside  of  the  embryo  blue,  and  when  the  cotyledons 
contain  reserve  food  dot  their  yellow  color  with  blue. 

8.  In  the  germinating  Lima  bean,  what  structures  grow 
most   rapidly  at   first  ?     Can   you   see   any  physiological 
reason  why  one  structure  should  develop  before  another  ? 
How  does  the  seedling  manage  to  rise  through  the  soil 
into  the  light  and  air  ? 

9.  Make  a  cross  section  of  the  main  root  where  a  whorl 
of  rootlets  arises,  and  show  by  a  drawing  the  method  of 
origin  of  the  rootlets.     What  advantage  do  you  see  in  the 
disposition  of  the  rootlets  in  a  regular  order  around  the 
main  root  ? 

10.  Follow  the  behavior  of  the  cotyledons,  and  try  in 
this  way  to  determine  their  functions.     In  your  judgment, 
at  what  stage  does  the  process  of  germination  cease  ? 

11.  After  two  or  more  sets  of  leaves  have  developed, 
make  drawings  to  show  their  position  on   the  stem  with 
reference  to  the  next  higher  or  lower  set.     What  signifi- 
cance do  you  see  in  a  regular  arrangement  of  the  leaves  ? 

12.  Examine  the  terminal  bud  of  the  seedling  with  a 
lens  and  determine  what  structures  develop  from  it. 

Castor  Bean. 

13.  Make   drawings  of   the   external   appearance  of   a 
castor  bean  from  the  two  most  important  points  of  view. 
Scale,   x  2. 


Seeds  and  Seedlings.  9 

14.  Carefully  remove  the  shell  or  testa  from  a  seed  and 
note  any  structural  details  thus  brought  to  light.     Split  the 
shelled  seed  longitudinally  through  its   greater  diameter, 
and    make    drawings    of    the   internal    structures.       Split 
another   shelled    seed    longitudinally    through    its    lesser 
diameter,  taking   care    to  cut  the  structures    already  dis- 
covered  exactly   through    the  middle.     Make   a  'drawing 
from  this  point  of  view,  sharply  demarking  the  limits  of 
the  different  structures.     Make  a  cross  section  of  a  shelled 
seed  a  little  below  the  middle,  and  draw  the  cut  surface, 
bringing   out  clearly  the  outlines  of  the    different    parts. 
These  drawings  should  all  be  made  to  the  scale,  x  3. 

Germinating  Castor  Bean. 

15.  Draw  the  castor  bean  in  the  first  stages  of  germina- 
tion, showing  how  the  seedling  protrudes  through  the  shell. 
Scale,  x  2. 

1 6.  Remove  the  testa  from  a  seed  in  the  first  stages  of 
germination,  and  split  it  in  halves  longitudinally  through 
the  broad  diameter.     Draw  from  the  point  of  view  of  the 
interior  surface.     Scale,   x    3.     Split  another  seed  in  the 
same  stage  of  germination  longitudinally  through  the  nar- 
row diameter,  taking  care  to  halve  all  of  the  structures, 
and  draw  from  the  cut  surface  to  the  same  scale. 

17.  Treat,  in  a  similar  manner,  seedlings  in  later  stages 
of  germination,  and  call  attention  to  any  new  structures 
which  were  not  seen  in  the  ungerminated  seed.     Follow 
the  changes  which  the  different  parts  undergo  up  to  the 
stage  where  all  reserve  food  materials  have  been  used  up. 

1 8.  In  your  notes,  answer  briefly  the  following   ques- 
tions :  Where  and  how  does  the  seedling  crack  the  hard 
shell  ?     How  does  the  seedling  get  above  the  soil  ?     How 
does  the  young  plant  get  the  food  materials  which  are 


lo  introduction  to   Botany. 

stored  up  for  its  use  in  germination  ?  How  does  it  differ 
from  the  embryo  of  the  Lima  bean  in  this  respect  ?  Com- 
pare the  means  of  protection  possessed  by  the  seed  of  the 
castor  bean  with  that  of  the  Lima  bean. 

Indian  Corn. 

19.  Make  drawings   of   the   exterior  appearance   of   a 
grain  of  Indian  corn,  from  the  two  points  of  view  which 
you  consider  the  most  important.     Scale,  x  2. 

20.  Remove  the  skin  from  a  soaked  grain,  and  if  any 
new  structures  are  revealed,  draw  to  the  same  scale.     In 
this  instance  and  in  all  grains  the  wall  of   the  ovary  in 
which  the  seed  is  formed  constitutes  a  part  of  the  skin. 

21.  Carefully  dissect  out  the  central  structures  from  a 
soaked   grain    and    draw  from   the   two  most   instructive 
points  of  view  to  the  scale,  x  3. 

22.  With  a  sharp  knife,  make  cross  sections  of  the  inner 
structures  on  either   side    of   the   center,    about   halfway 
toward  each  apex.     Examine  with  a  lens,  and  draw  to  a 
scale  large  enough  to  show  all  that  the  lens  has  revealed. 

23.  Halve  a  soaked  grain  longitudinally  through   the 
lesser  diameter,  making  a  sliding  cut  with  a  sharp  knife 
so  as  to  secure  smooth  surfaces.     If  the  knife  does  not 
pass  through  the  middle  of  the  structures,  carefully  trim 
the  larger  piece  until  an  exactly  central  section  is  secured. 
Draw  the  cut  surface.     Scale,  x  3.     Place  a  drop  of  iodine 
solution  on  the  cut  surface,  and    after  a  minute  draw  it 
off  with  filter  paper.     The  iodine  will   color   the  starchy 
parts  of  the  seed  a  deep  purple. 

Germinating  Indian  Corn. 

24.  Make    drawings    of    the   external    appearance    of 
germinating  Indian  corn  in  successive  stages  of  develop- 
ment.    Scale,  x  1.5. 


Seeds  and  Seedlings.  1 1 

25.  Make  a  median    longitudinal  section    through   the 
lesser  diameter  of  seedlings  in  various  stages  of  germina- 
tion, and  draw  from  the  point  of  view  of  the  cut  surfaces. 
The  drawings  should  show  definitely  the  changes  which 
the  several  parts  undergo  as  germination  progresses. 

26.  Make  cross  sections  of  the  stem  of  a  well-advanced 
seedling,    and    drawings    to    show   how    the    leaves   are 
wrapped  together,  as  shown  by  these  sections. 

27.  What  are  the  differences  in  the  details  of  growth  of 
Lima  bean,  castor  bean,  and  Indian  corn  which  result  in 
the  grain  of  corn  remaining  below  the  ground  in  germina- 
tion, while,  in    the  beans,  the  bulk  of  the  seed  is   lifted 
above  the  ground  ?     By  what  means  does  the  corn  seed- 
ling obtain  the  food  which  is  stored  in  the  seed  ? 

28.  After  the  instructor  has  pronounced  the  drawings 
of  castor  bean  and  Indian  corn  satisfactory,  tint  the  dif- 
ferent structures  with  the  colored  pencils,  as  in  the  case 
of  the  Lima  bean,  using  the  same  color  for  the  correspond- 
ing parts  in  all  of  the  seeds  and  seedlings  studied. 

General  Comparisons. 

29.  Make  drawings  on  one  page,  for  comparison,  of  the 
seeds  of  Lima  bean,  castor  bean,  and  Indian  corn,  select- 
ing  the   point  of    view   which   best   shows   the   different 
structures,  and    with    the  colored   pencils  give   the  same 
colors  to  the  corresponding  parts. 

30.  In    your  notes  briefly  compare  the    corresponding 
parts  of  the  seeds  studied. 

Experiments. 

31.  With  the   sharp  point  of  a  penknife,  scrape  up  a 
small  portion  from  the  cotyledon  of  a  soaked  Lima  bean 
and  mount  in  a  drop  of  iodine  solution  (see  page  387),  on 
a  glass  slip,  and  cover  with  a  coverglass.     Examine  with 


12  Introduction  to   Botany. 

a  compound  microscope,  using  a  |  or  J  inch  objective. 
Starch  grains  will  be  seen  of  various  shades  of  purple, 
depending  on  the  degree  of  action  of  the  iodine ;  while 
other  granules,  whose  substance,  called  proteid,  is  closely 
related  chemically  to  the  white  of  an  egg,  will  appear 
from  yellow  to  brown.  These  are  the  two  chief  classes  of 
reserve  food  in  the  seed  of  Lima  bean.  The  fact  that  starch 
is  present  in  large  quantities  is  manifest  by  the  deep 
purple  color  which  appears  when  a  piece  of  cotyledon  is 
placed  in  a  drop  of  iodine.  A  compound  microscope 
would  therefore  not  be  necessary  to  demonstrate  the  mere 
presence  of  starch. 

32.  Mount  in  a  drop   of   iodine,   as   before,   scrapings 
from  the  cut  surface  of  soaked  Indian  corn,  and  note  the 
presence  of  both  starch  and  proteid. 

33.  Treat  in  a  similar  manner  some  scrapings  from  the 
reserve  food  materials  of  castor  bean.     The  regular  brown 
bodies  are  proteid,  while  the  irregular  yellow  or  brown 
bodies  and  circular  masses  of  varying  sizes  are  castor  oil. 

34.  Boil  in  Fehling's  solution  (see  page  385)  in  a  test 
tube  a  dry  crushed  seed  of  Lima  bean,  and  note  whether 
the  presence  of  glucose  is  demonstrated  by  the  production 
of  a  red  precipitate  of  cuprous  oxide.     Treat  in  a  similar 
manner  a  seedling  which  is  somewhat  advanced  in  germi- 
nation, and  seeds  and  seedlings  of  castor  bean  and  Indian 
corn.     State   in    your   notes   your   deductions   as   to   the 
changes  which  the  reserve  materials  in  seeds  undergo  in 
the  process  of  germination. 

35.  Place  moist  white  pine  sawdust  to  the   depth   of 
about  an  inch  in  four  wide-mouth  bottles.1 

Put  several  grains  of  Indian  corn  that  have  lain  in  water 
over  night  into  two  of  these.     Cover  the  corn  with  about 

1  Such  as  No.  2750  in  the  catalogue  of  Whitall,  Tatum,  &  Co.,  Philadelphia. 


Seeds  and  Seedlings.  13 

half  an  inch  of  the  moist  sawdust,  and  press  down  firmly. 
Cork  the  four  bottles  tightly  (two  containing  the  seeds  in 
moist  sawdust,  and  two  containing  sawdust  only)  and  leave 
over  night  in  a  warm  place.  The  following  day  fasten  a 
piece  of  tallow 'candle  or  wax  taper  to  a  wire  handle  ;  light 
the  candle ;  remove  the  cork  from  one  of  the  bottles  con- 
taining sawdust  only,  and  slowly  lower  the  lighted  candle 
into  the  bottle  until  it  rests  upon  the  sawdust.  Leave  the 
candle  in  this  position  for  some  time,  and  note  whether 
there  is  a  tendency  for  the  flame  to  become  extinguished. 
Remove  the  cork  from  one  of  the  bottles  containing  the 
seeds  and  lower  the  lighted  candle  into  it.  If  the  seeds 
have  been  germinating  properly,  the  flame  will  quickly 
expire.  What  do  you  conclude  from  these  observations  ? 

36.  Prepare  limewater  as  described  on  page  387 ;  pour 
some  of  the  clear  liquid  into  a  clean,  wide-mouth  bottle ; 
then  remove  the  cork  from  the  remaining  bottle  of  seeds, 
and,  holding  the  mouth  of  the  bottle  close  down  over  the 
mouth  of  the  bottle  of  limewater,  pour  the  gas  from  the 
bottle  of  seeds  (as  if  pouring  water)  into  the  bottle  of  lime- 
water.     Cork  the  bottle  of   limewater   tightly  and  shake 
vigorously.     The  white  precipitate  of  calcium   carbonate 
now  appearing  in  the  water  has  resulted  from  the  reaction 
between  the  carbon  dioxide  gas  from  the  bottle  of  seeds, 
and  the  calcium  hydrate  of  the  limewater.     See  whether 
the  air  in  the  second  bottle  containing  sawdust  only  gives 
a  like  result.    Shake  up  some  limewater  in  a  bottle  contain- 
ing only  ordinary  atmosphere,  to  see  whether  the  precipi- 
tate is  really  produced  by  the  gas  poured  from  the  bottle 
of  seeds. 

37.  To  demonstrate  the  identity  between  the  gas  given 
off  by  germinating  seeds  and  a  gas  produced  by  a  burning 
candle,   or   by  breathing,   perform   the   following    experi- 


14  Introduction  to  Botany. 

ments :  Hold  a  lighted  candle  in  the  mouth  of  an  inverted 
bottle  until  the  candle  is  extinguished.  Cork  the  bottle, 
set  it  right  side  up,  and  give  the  gas  in  it  time  to  cool. 
Then  pour  limewater  into  the  bottle  and  shake  vigorously. 
The  white  precipitate  will  be  produced  as  before.  Blow 
the  breath  through  a  straw  or  glass  tube  into  another  bot- 
tle of  limewater,  holding  the  tube  close  to  the  bottom  so 
that  the  breath  will  bubble  through  the  limewater.  After 
this  process  has  continued  for  a  short  time  the  white  pre- 
cipitate of  calcium  carbonate  will  be  observed. 

38.  It  would  seem  from  these  results  that  a  chemical 
process  takes  place  in  germinating  seeds  similar  to  that 
which  occurs  in  our  breathing,  or  in  the  burning  of  a  candle. 
It  will  be  interesting  to  note  whether  this  process  is  asso- 
ciated with  visible  changes  in  the  reserve  food  supply  in 
the  seed.     Scrape  a  small  portion  from  the  reserve  food  of 
a  soaked  grain  of  corn,  and  mount  under  a  coverglass  in  a 
drop  of  water;  examine  with  a  high  power.     Treat  in  a 
like  manner  some  of  the  remnant  of  reserve  material  still 
remaining  in  the  grain  attached  to  a  far-advanced  seedling. 
The  starch  grains  in  the  latter  preparation  show  erosions 
like  those  shown  in  Fig.  3,  page  21. 

39.  To  estimate  the  value  of  the  reserve  materials  in 
seeds  to  resumption  of  growth  of  the  embryo,  perform  the 
following  experiments :    Plant  seeds  of  Lima  bean  in  saw- 
dust, chopped  sphagnum,  or  other  suitable  seed  bed,  and 
after  the  young  plants  appear,  remove  the  cotyledons  from 
some  of  them,  and  leave  others  in  their  normal  condition. 
Compare  the  rate  of  growth  of  the  two  sets  of  seedlings. 
Soak  grains  of  corn  in  water  over  night,  and  remove  the 
outer  food   supply  down  to  the  fleshy  cotyledon.     Plant 
both  depleted  and  normal  grains  in  moist  s.  ^nd  note 
their  relative  rates  of  growth.     Try  a  similar  ext     "  ^«^f 


Seeds  and  Seedlings.  15 

with  Lima  beans,  removing  the  cotyledons  from  soaked 
seeds,  and  planting  the  much  diminished  embryos,  together 
with  normal  seeds,  in  moist  sawdust.  Make  comparisons 
of  the  results  of  all  of  the  experiments  of  this  kind,  and 
write  out  your  conclusions  in  full.  This  experiment  will 
be  more  certain  to  succeed  if  the  sawdust  has  been  boiled, 
to  destroy  moulds  and  bacteria. 

40.  Soak  seeds  of  barley  in  water  over  night,  and  plant 
in  moist   sawdust   in  a  wide-mouth  bottle ;    place  in  the 
bottle  a  test  tube  containing  a  strong  solution  of  pyrogallic 
acid  and  caustic  potash ;  cork  the  bottle  tightly  by  shov- 
ing the  cork  to  a  short  distance  below  the   rim    of   the 
bottle  and    filling  in  over  the   cork  with    melted   sealing 
wax.     Prepare  another  set  of  seeds  in  the  same  way,  but 
with  a  potash  solution  only  in  the  test  tube.     The  pyro- 
gallic acid  in  its  alkaline  solution  absorbs  the  oxygen  from 
the  atmosphere  in  the  bottle,  while  the  caustic  potash  in 
both  instances  absorbs  the  carbon  dioxide  of  the  atmos- 
phere, and  that  which  is  produced  by  the  germination  of 
the  seeds ;  the  conditions  are,  then,  as  follows :  one  bottle 
lacks  oxygen  and  carbon  dioxide,  while  the   other   lacks 
only   the   carbon   dioxide.     The   experiment   is   designed 
to  answer  the  question  whether  oxygen  is  necessary  to 
germination.      Let   the   experiment   continue   for   several 
days,   keeping   the   bottles   in   a   dark   and   warm   place. 
Record  the  results  of  your  observations. 

41.  Remove  the  glass  front  and  the  hands  from  a  cheap 
alarm  clock.     Provide  a  soft  pine  block  about  an  inch 
square,  whittle  one  end  to  a  taper,  and  drill  a  small  hole 
into  it,  so  that  it  will  slip  through  the  opening  of  the  dial 
face  and  tightly  over  the  hour-hand  spindle.      Fasten   a 
Petri1  dish  toy~.:e  outer  face  of  the  pine  block  by  a  melted 

1  See  catalogues  of  dealers  in  bacteriological  supplies. 


1 6  Introduction  to  Botany. 

mixture  of  one  third  beeswax  and  two  thirds  rosin,  taking 
care  to  center  the  dish  with  the  hour-hand  spindle.  Pack 
moist  pine  sawdust  into  the  dish,  level  with  the  surface,  and 
press  soaked  grains  of  corn  into  the  sawdust,  not  very 
tightly,  broad  face  down,  but  do  not  cover  them  with  the 
sawdust.  Put  on  the  cover  of  the  Petri  dish,  and  hold  it 
in  position  by  means  of  clips  made  of  spring  brass  wire. 
(See  Figs.  7  and  8.)  Wind  the  clock  and  set  it  in  its  nor- 
mal position  ;  that  is,  with  the  hour-hand  spindle  horizontal. 
Prepare  seeds  in  another  dish  in  exactly  the  same  manner, 
but  fasten  it  so  that  it  will  stand  vertically  on  its  edge. 

In  the  first  experiment  the  directive  effect  of  gravity 
will  be  neutralized  by  the  revolution  of  the  dish,  while  in 
the  second,  gravity  may  exercise  its  usual  influence  on  the 
direction  taken  by  root  and  shoot.  Since  the  seeds  are 
not  covered  by  the  sawdust,  their  progress  in  germination 
may  be  observed  at  any  time  without  interrupting  the 
experiment.  The  position  occupied  by  the  parts  of  the 
seedlings  can  easily  be  recorded  for  any  period,  by  tracing 
with  ink  on  the  cover  immediately  over  them. 

DISCUSSION. 

5.  Nature  and  Purpose  of  Seeds.  —  A  seed  is  essentially 
a  young  plant  produced  sexually  by  a  flower  (see  page  168). 
The  young  plant  has  temporarily  ceased  to  grow,  and 
has  been,  or  is  to  be,  cast  off  from  the  parent  plant, 
having  first  been  provided  with  reserve  food  materials 
necessary  to  the  resumption  of  growth,  and  with  certain 
means  of  protection.  The  purpose  of  the  seed  is  to 
insure  the  continuation,  multiplication,  and  locomotion  or 
distribution  of  the  species.  Many  plants  are  too  tender  to 
survive  the  cold  of  winter,  or  the  dry  seasons  of  those 
regions  where  the  rain  does  not  fall  for  many  months  of 


Seeds  and  Seedlings.  17 

the  year.  But  the  dry  seeds  of  these  plants  can  withstand 
great  extremes  of  heat  and  cold,  and  do  not  need  water  to 
keep  them  alive ;  indeed,  the  ability  of  seeds  to  survive 
adverse  seasons  is  due  in  large  measure  to  the  small  amount 
of  water  which  they  contain.  Since  seeds  as  a  rule  retain 
their  vitality  for  several  years,  in  some  cases,  indeed,  for 
twenty-five  or  even  fifty  years,  they  can,  if  necessary,  tide 
a  species  over  one  or  more  years  which  are  unfavorable  to 
growth. 

6.  Multiplication  by  Seeds.  —  A  single  plant  of  Indian 
corn  produces  on  the  average   about   130  grains  of  corn, 
which,  under  the  favorable  conditions  resulting  from  culti- 
vation, might  in  the  succeeding  season  give  rise  to  16,900 
grains.     An   example    of   this   kind  will  serve  to  demon- 
strate the    immense  capacity  of  multiplication   by  means 
of  seeds ;  although  under  natural  conditions  only  a  small 
portion    of   the    seeds    produced    ever   result    in    mature 
plants. 

7.  Migration  by  Seeds. — Since  land  plants  must  draw 
their  water  and  some  other  raw  food  materials  from  the 
soil,  it  is  of  great  advantage,  and  even  necessary,  for  them 
to  be  fixed  in  the  soil  by  means  of  their  roots.     While  the 
individual  is  thus  anchored,  the  species  is  still  able  to  move 
from  place  to  place  by  means  of  the  seeds.     In  this  way, 
species  have  migrated  through  the  long  geological  periods 
from  regions  which  were  becoming  unhabitable  to  others 
which  were  more  favorable  ;  and  by  this  means  the  borders 
of  continents  which  are  rising  from  the  oceans,  and  newly 
formed  volcanic   or   coral   islands,   become   colonized   by 
plants  from  greater  or  less  distances.     It  is  a  matter  of 
common  observation  that  tracts  of  land  which  have  been 
protected  from  grazing  animals  become  inhabited  in  the 
course  of  a  few  years  by  plants  which  were  never  seen 


1 8  Introduction  to  Botany. 

there  before ;  and  that  treeless  areas  along  the  borders  of 
streams  soon  become  overgrown  with  dense  groves  of 
cottonwood  and  willow  saplings  after  cattle  are  excluded, 
the  seeds  in  some  instances  having  come  several  miles 
from  the  homes  of  their  ancestors. 

8.  Food  and  Protection.  —  In  order  fully  to  understand 
the  significance  of  the  various  structures  of  a  seed,  we  must 
keep  in  mind  its  functions  of  continuance,  migration,  and 
multiplication,  and  the  conditions  under  which  these  func- 
tions must  be  performed.  It  is  of  great  importance  that 
the  young  plant  in  the  seed  be  protected  against  unfriendly 
contingencies.  We  find  that  mechanical  injuries  are  pre- 
vented either  by  the  extreme  hardness  of  the  embryo  and 
reserve  food,  as  in  the  case  of  Lima  bean  and  Indian  corn ; 
or,  if  the  embryo  and  reserve  food  are  oily  and  soft,  by  a 
covering  of  stony  hardness,  such  as  the  castor  bean  and 
various  nuts  possess.  The  reserve  food  materials  are 
packed  tightly  into  the  seed,  and  in  a  form  which  is,  for 
the  most  part,  insoluble  in  water,  and  on  that  account 
more  certain  of  preservation  within  the  seed. 

In  some  seeds  the  reserve  material  is  stored  entirely 
within  the  embryo,  as  in  Lima  bean  ;  in  others  it  is  partly 
within  and  partly  without  the  embryo,  as  in  Indian  corn ; 
while  in  others,  such  as  the  castor  bean,  it  lies  wholly  out- 
side the  embryo.  But  this  variation  in  the  location  of  the  re- 
serve food  seems  to  have  little  significance  so  far  as  concerns 
germination,  for  in  all  cases  it  is  finally  transferred  to  the 
growing  parts  of  the  seedling  ;  and  whether  this  takes  place 
before  the  seed  is  cast  from  the  parent  plant,  or  only  during 
the  stages  of  germination,  is  apparently  indifferent  to  the 
well-being  of  the  young  plant.  The  facts  of  significance 
are,  that  the  embryo  plant  is  alive,  although  in  a  tempo- 
rary state  of  inactivity ;  that  it  has  a  sufficient  store  of 


Seeds  and  Seedlings. 


food  materials  locked  in  against  loss ;  and  that  the  plant 
is  not  inclined  to  spring  into  activity,  nor  are  the  reserve 
materials  liable  to  become  unlocked  except  in  the  right 
season  and  under  the  proper  conditions  for  the  establish- 
ment of  the  young  plant  as  an  independent  individual, 


FIG.  i. 

Germination  of  the  Mangrove.  /,  longitudinal  section  of  the  Mangrove  flower; 
y,  the  fruit ;  K,  the  seed  germinating  while  yet  contained  in  the  fruit  hanging  to 
the  tree  (compare  //) ;  L,  longitudinal  section  of  the  fruit  showing  the  seedling 
separating  from  it ;  H,  branch  of  the  Mangrove  with  seedlings  pendent  from  it 
and  others  that  have  fallen  and  taken  root  in  the  moist  soil.  After  K.ERNER. 

with  its  roots  in  the  soil,  and  its  leaves  spread  out  in  the 
sunlight  and  air. 

9.  Time  of  Germination.  —  Some  seeds  are  capable  of 
germination  as  soon  as  mature,  and  even  before  they  are 
cast  off  from  the  parent  plant.  One  may  sometimes  see 
wheat  germinating  in  the  standing  ears  before  harvest. 


2O 


Introduction  to  Botany. 


The  mangrove  is  a  notable  example  of  a  plant  whose 
seeds  habitually  pass  through  the  first  stages  of  germina- 
tion before  falling  from  the  tree  (see  Fig.  i).  In  most 
cases,  however,  the  seeds  must  go  through  a  greater  or 
less  period  of  rest  before  they  are  in  a  condition  for  ger- 
mination ;  and  during  this  period  of  comparative  inactivity, 
ferments  are  possibly  being  formed  which  are  necessary 

to  render  the  starches,  oils,  and 
some  forms  of  proteid  soluble  in 
the  cell  sap. 

10.  Conditions  Necessary  to  Ger- 
mination.— Until  the  internal  con- 
ditions are  favorable  through  the 
formation  of  ferments,  etc.,  the 
seed  cannot  germinate,  but  cer- 
tain external  conditions  are  also 
necessary  to  germination.  These 
are  the  presence  of  oxygen,  water, 
a  certain  degree  of  heat. 
While  some  seeds  have  been 
known  to  germinate  at  tempera- 
tures quite  close  to  the  freezing  point,  most  seeds  germinate 
best  between  16°  and  27°  C.  (60.8°  and  80.6°  F.).  This  sig- 
nifies that  until  a  certain  amount  of  energy  in  the  form 
of  heat  is  afforded  to  seeds  from  the  outside,  some  of  the 
necessary  processes  attending  growth  cannot  be  initiated. 
Neither  can  germination  begin  until  the  seed  has  absorbed 
sufficient  water  to  stretch  its  tissues  and  act  as  the  solvent 
for  its  reserve  food  materials.  Some  seeds  are  able  to 
absorb  water  until  their  tissues  are  stretched  by  a  force 
equal  to  about  200  pounds  per  square  inch ;  and  it  is  this 
stretching  force  which  starts  the  increase  in  size  of  the 
embryo  plant.  If  oxygen  is  excluded  from  seeds,  they  will 


FIG.  2. 

Photomicrograph  of  Starch  Grains     and 
in  a  section  of  a  grain  of  Indian 
corn.    Highly  magnified. 


Seeds  and  Seedlings.  21 

not  germinate,  although  all  other  conditions  are  favorable. 
The  oxygen  serves  a  double  purpose  in  helping  to  form 
new  soluble  and  diffusible  compounds  from  the  reserve 
materials,  and  in  sustaining  the  respiration  of  the  embryo 
as  it  becomes  quickened  into  renewed  growth.  The  neces- 
sity of  oxygen  to  germination  has  been  demonstrated  by 
Experiment  40,  page  15,  but  it  is  also  frequently  demon- 
strated in  nature  by  the  fact  that  most  seeds  will  not 
germinate  in  a  water-soaked  soil ; 
notable  exceptions  are  the  seeds 
of  some  water  plants,  such  as 
those  of  Nelumbo,  which  are  able 
to  obtain  sufficient  oxygen  from 
the  water. 

11.  Digestive  Ferments.  —  The  FIG 
insoluble    and    poorly    diffusible   , 

*  "Photo micrograph  or  Starch  Grams 

reserve  materials  are  rendered  from  a  grain  of  Indian  com  in 
soluble  and  diffusible  by  means  an  advanced  stase  of  sermina- 

•*  tion. 

of  ferments  present  in  the  seeds. 

The  ferment  which  attacks  starch  is  known  as  diastase. 
The  result  of  its  work  can  be  seen  by  a  comparison  of 
Figs.  2  and  3,  which  are  photomicrographs  of  starch  grains 
from  ungerminated  and  germinating  seeds  of  Indian  corn. 
In  Fig.  3  it  is  seen  that  the  grains  have  been  much  eroded 
around  the  border  and  throughout  their  whole  structure  by 
the  action  of  the  diastase. 

12.  Circulation  of  Reserve  Materials.  —  After  the  reserve 
materials  have  been  rendered  soluble  in  the  cell  sap,  and 
diffusible  through  the  cell  membranes,  they  move  from  the 
cells  in  which  they  are  stored,  by  the  processes  of  diffusion 
(see  page  36),  to  the  growing  regions  of  the  embryo,  there 
to  be  used  in  part  in  the  building  up  of  new  tissues,  and  in 
part  to  be  consumed  by  combustion  or  respiration.     It  is 


22 


Introduction  to  Botany. 


this  process  of  respiration  which  consumes  oxygen  and  gives 
off  carbon  dioxide  (see  Experiment  37),  and  in  so  doing 

makes  active  the  internal  energy 
^\  necessary  to  life  and  growth. 

In  seeds  having  the  reserve 
materials  stored  in  the  cotyledons, 
as  in  the  Lima  bean,  the  reserve 
materials  need  only  to  pass  from 
these  into  the  other  parts  of  the 
embryo,  leaving  the  cotyledons  in 
a  shrunken  condition ;  but  in  the 
case  of  such  seeds  as  those  of 
FIG.  4.  corn  (Fig.  4)  and  castor  bean, 

Median  longitudinal  section    where  the   reserve    materials  lie 

through  a  grain  of  Indian  corn.  ,    .  j          r     , ,  •,  r 

The  median  diagonal  line  de-   outside   of   the    embryo   for   the 
marks  the  endosperm  or  reserve    greater  part,  at  least,  the  cotyle- 

food  of  the  upper  half  from  the      ,  11- 

embryo  occupying  the  lower   dons    act    as    absorbing    organs, 

half  of  the  grain.     The  fleshy     and   enlarge   as    germination    pro- 
cotyledon  constituting  the  larger  ,  ,  .         , 
part  of  the  embryo  surrounds     CCeds  SO  as  to  keep  in  close  COn- 

the   plumule    and    hypocotyi   tact  with    the    diminishing   food 

above    and    below.      Photomi-  *•*«••• 

crograph  x  3.  supply.     This  is  also  well  illus- 

trated in  the  seed  of  the  date, 

where  the  cotyledon  is  like  that  of  the  corn  in  serving 
chiefly  as  an  absorbing  organ. 

In  the  seeds  of  the  corn  and  date  type  the  ferments  lie 
partly  within  the  cotyledon  and  partly  within  the  cells  which 
bear  the  food  materials.  As  the  reserve  materials  of  the 
date  seed,  consisting  chiefly  of  cellulose  of  bony  hardness, 
become  converted  into  sugar,  they  are  absorbed  by  the  coty- 
ledon, which  then  enlarges  and  occupies  the  space  thus 
vacated  (see  Fig.  5).  In  this  way  the  cotyledon  keeps  in 
close  contact  with  the  reserve  materials  and  transports 
them  from  the  seed  as  fast  as  they  are  rendered  soluble ; 


Seeds  and  Seedlings. 


a  fact  of  great  importance,  since  the  action  of  the  ferments 
is  hindered  or  entirely  pre- 
vented if  their  products  are 
allowed  to  accumulate  within 
their  field  of  action. 

A  very  notable  example 
of  the  enlargement  of  the 
cotyledon  while  serving  as 
an  absorbing  organ  is  seen 
in  the  cocoanut.  Here  the 
embryo  is  relatively  small 
and  lies  embedded  in  the 
fleshy  reserve  food  at  the 
pointed  end  of  the  nut.  As 
germination  proceeds,  a  part 
of  the  cotyledon  grows  out 
through  one  of  the  three 
openings  in  the  shell,  and 
carries  the  plumule  and  hy-  FIG.  5. 

pOCOtyl    OUt    with     it,    while    Stages  in  the  germination  of  a  Date  Seed  : 

I,  the  young  plant  still  attached  to  the 

the  greater  part  of  the  coty- 
ledon remains  within  the 
seed,  and  as  it  absorbs  the 
reserve  materials  it  enlarges 
and  fills  the  cavity  (see  Fig. 6). 
13.  Direction  of  Growth.  — 
The  root  of  the  seedling 
grows  downward  into  the 
soil,  and  the  shoot  (stem  and 
leaves)  upward  into  the  sun- 
light and  air,  and  it  matters 
not  in  what  direction  the 
seed  may  be  lying  in  the  soil. 


seed ;  2,  cross  section  through  a  seed 
showing  the  small  embryo  to  the  left 
embedded  in  the  hard  cellulose  endo- 
sperm ;  3,  cross  section  of  a  seed  in  an 
early  stage  of  germination ;  4,  section 
through  a  seedling  in  an  advanced  stage 
of  germination.  The  cotyledon  remains 
in  the  seed  and  enlarges  as  the  endo- 
sperm is  absorbed.  The  stem  or  peti- 
ole of  the  cotyledon  depending  from  the 
seed  enlarges  at  its  base  and  covers  the 
plumule.  The  tapering  end  below  the 
plumule  is  the  hypocotyl.  5,  a  later 
stage  showing  the  endosperm  nearly  ex- 
hausted and  the  cotyledon  filling  the 
cavity ;  6,  surface  view  of  a  seed  in  an 
early  stage  of  germination.  After  SACHS. 

The  hypocotyl  may  be 


Introduction  to  Botany. 


pointing  upward,  but  as  the  root  grows  forth  it  turns  sharply 
downward,  and  the  shoot  as  it  develops,  sharply  upward. 

This  is  brought  about  by  the  in- 
fluence of  gravity. 

In  just  what  way  gravity  can 
exert  such  an  influence  is  not 
known.  We  are  accustomed  to 
think  of  gravity  as  invariably  at- 
tracting bodies  toward  the  cen- 
ter of  the  earth,  but  on  living 
and  growing  bodies  it  may  exert 
an  influence  of  quite  another 
character.  We  might  conclude, 
without  an  experiment,  that 
gravity  is  the  directive  force ; 
for  whether  seeds  are  germinat- 
ing near  the  poles  or  at  the 
equator,  the  roots  always  turn 
end  view  toward  tfte  center  of  the  earth, 
of  the  "  cocoanut "  or  stone  of  the  and  the  shoots  away  from  it.  It 

fruit  (corresponding  to  the  stone  i  -, 

of  a  peach),  showing  the  dividing  1S>  however,  a  simple  matter  to 
lines  of  the  three  carpels  which  eliminate  the  directive  influence 

compose  the  fruit.     The  embryo       r  .    •  •,  ,          -, 

emerges  through  the  lower  open-    °f  graVlty,  and  by  observing  the 

ing.     B,   longitudinal    section  growth  of  seedlings  under  such 

through  the  fruit  of  the  cocoanut, 

showing  the  embryo  in  process  of  circumstances  to  determine  what 
germination ;    e,  the  stone  sur-  effect  gravity  is  producing  under 

rounding  the  fleshy  endosperm;  ...  _. 

/  the  enlarging  cotyledon.     The    normal     Conditions.       Figures     / 

plumule    is    growing    upward  ancj  g   illustrating  the  result  of 

through    the    fibrous   outer   coat 

of  the  fruit.     This  coat  is  re-  Experiment  41,  page  15,  show 

moved  before  the  cocoanuts  are    how  the  influence  of  gravity  may 
marketed.     After  WARMING.  * 

be  demonstrated  by  removing  it 

from  one  set  of  seedlings  while  it  is  still  operative  on 
another  set. 


rIG.  o. 
Fruit  of  the  Cocoanut : 


Seeds  and  Seedlings. 


If  seeds  are  planted  in  a  pan  of  sawdust  which  is  kept 
revolving  rapidly  in  a  horizontal  plane,  centrifugal  force 
may  be  made  to  overcome  gravity,  so  that  the  roots  grow 
away  from  the  axis  of  rotation  and  the  shoots  toward  it 
(see  Fig.  9). 


FIG.  7. 

Seedlings  of  Indian  corn  grown  in  saw- 
dust in  a  Petri  dish  while  revolving 
by  clockworks  one  revolution  per 
hour.  The  axis  of  revolution  is  hori- 
zontal, the  plane  of  the  dish  vertical. 
Gravity  as  a  directive  agent  is  elimi- 
nated, and  roots  and  shoots  grow  out 
in  the  direction  in  which  they  happen 
to  be  pointed. 


FIG. 


Seedlings  of  Indian  corn  grown  in  saw- 
dust in  a  Petri  dish  which  was  kept 
stationary  in  a  vertical  plane  in  the 
position  shown  in  the  figure.  Gravity 
is  acting  as  a  directive  agent,  and  the 
roots  find  and  take  the  downward  and 
the  shoots  the  upward  direction,  irre- 
spective of  the  directions  toward  which 
they  were  originally  pointing. 


Whatever  part  plants,  as  living  beings,  have  taken  in 
the  selection  of  gravity  to  direct  their  growth,  a  wonderful 
discrimination  has  been  exercised ;  for,  of  the  possibly 
available  forces  of  nature,  gravity  is  the  only  one  which 
is  practically  constant  in  its  strength,  and  in  its  direction 
of  action,  through  all  times  of  day  and  seasons,  and  in 
all  positions  over  the  earth's  surface.  The  seedling  can 
therefore  depend  with  certainty  on  its  root  and  shoot 
taking  the  right  directions  irrespective  of  the  position  in 


26  Introduction  to  Botany. 

which  the  seed  may  be  lying  in  the  soil,  or  of  the  time  or 
place  of  its  germination. 


FIG.  9. 

Seedlings  of  Indian  corn,  beans,  and  peas  grown  in  moist  sawdust  in  a  pan  17 
inches  in  diameter,  which  was  kept  revolving  at  the  rate  of  185  revolutions  per 
minute.  The  seeds  were  planted  beneath  the  surface,  and  the  seedlings  have 
been  uncovered  for  the  photograph. 

14.  Roots  the  First  to  Grow. — It  has  been  noticed  that  the 
root  first  grows  out  and  becomes  established  in  close  con- 
nection with  the  soil  before  the  other  parts  of  the  embryo 
emerge  above  the  surface.  This  insures  that  the  seedling 
may  not  easily  be  dislodged  from  its  position,  and  that  the 
parts  which  are  soon  to  be  exposed  to  the  drying  influence 
of  sun  and  winds  may  continually  be  supplied  with  water 
from  the  soil. 

If  a  seedling  is  removed  with  care  from  a  sandy  loam, 
the  soil  will  be  found  adhering  to  the  roots  in  large,  loose 
masses,  and  when  the  soil  is  carefully  washed  away  in 
water,  it  will  be  seen  to  have  been  bound  together  by 
means  of  numerous  fine  hairs  growing  from  the  roots.  It 


Seeds  and  Seedlings.  27 

will  be  found  very  difficult  to  remove  all  of  the  particles 
from  these  hairs,  so  intimate  is  their  union.  The  signifi- 
cance of  this  close  relation  will  be  discussed  in  another 
chapter. 

15.  Completion  of  Germination.  —  After  the  roots  have 
become  established  in  the  soil,  and  the  green  leaves  have 
unfolded  to  the  sunlight,  the  young  plant  is  in  position  to 
form  its  own  food  materials,  and  to  be  no  longer  depend- 
ent on  food  provided  by  the  parent  plant.     The  mother 
plant,  however,  often  provides  more  than  sufficient  food  to 
bring  the  offspring  to  a  position  of  independence ;  for,  in 
many  instances,  the  reserve  food  is  not  exhausted  until 
long  after  the  leaves  and  roots  are  ready  to  take  up  their 
office  of  providing  new  food  supplies.     The  reserve  mate- 
rials in  the  cotyledons  of  the  oak,  for  example,  do  not 
become   exhausted   until  the  close  of  the  second   year's 
growth.     The  process  of  germination  may  be  considered 
completed  when  the  seedling  is  ready  to  provide  for  itself, 
for  it  would  be  manifestly  incongruous  to  speak  of  the 
young   oak  at  the  beginning  of  the  second   year  of  its 
existence  as  still  in  the  process  of  germination. 

16.  Size  of  Seeds. — The  size  of  the  seed  appears  to  have 
little  or  no  relation  to  the  size  of  the  parent  plant.     The 
cocoanut  and  cottonwood  trees  are  both  large  trees  when 
fully  grown,  yet  the  cocoanut,  as  we  find  it  on  our  market, 
weighs   about    750  grams  (including   the  shell  or  stone, 
which  is  not  a  part  of  the  seed),  while  a  cottonwood  seed 
as  it  floats  from  the  tree  weighs  about  0.0015  gram.    What 
the  size  and  rate  of  growth  of  the  plant  shall  be  depends 
upon  potentialities  transmitted  to  the  seed  from  the  parent 
plant  that  are  quite  beyond  our  powers  of  observation. 


CHAPTER    III. 
ROOTS. 

OBSERVATIONS. 

42.  Nearly  fill  two  wide-mouth  bottles  with  a  soil  com- 
posed of  one  third  black  loam,  one  third  rotted  manure, 
and  one  third  sifted  sand.     In  one  bottle,  plant  a  soaked 
seed  of  Indian  corn,  and  in  the  other  a  soaked  seed  of  Lima 
bean,  and  incline  the  bottles  at  an  angle  of  45°.     Notice 
whether  the  roots  take  the  same  direction  in  both  cases. 
If  any  of  the  roots  reach  the  side  of  the  bottle,  note  the 
behavior  of  their  tips  as  they  make  their  way  between  the 
soil  particles.     Study  with  a  lens  and  note  the  relation  of 
the  root  hairs  to  the  soil  particles.     How  close  to  the  apex 
of  the  root,  and  how  far  back  from  the  apex,  do  the  root 
hairs  grow  ? 

43.  Soak  seeds  of  barley  in  water  over  night,  and  plant 
between  pieces  of  moist  carpet  paper,  or  blotting   paper, 
about  three  inches  square.     Prepare  seeds  thus  for  each 
student.     Keep  in  a  covered  dish  in  a  warm  place,  and  do 
not  allow  the  paper  to  become  dry.     After  the  roots  have 
grown  out  for  an  inch  or  more  make  drawings  to  show  the 
root  hairs. 

44.  Place  a  piece  of  polished  marble  at  the  bottom  of  a 
flower  pot,  or,  instead  of  the  marble,  a  clam  or  oyster  shell 
with  the  concave  side  up.     Nearly  fill  the  pot    with  the 
soil  mixture  above  described,  and  plant  in  it  a  few  seeds  of 
soaked  Indian  corn.     After  a  few  weeks,  if  the  corn  has 

28 


Roots.  29 

made  a  good  growth,  remove  the  soil  from  the  pot  and 
note  the  effect  of  the  roots  on  the  surface  of  the  marble  or 
shell.  Does  this  teach  anything  as  to  the  possible  effect 
of  the  roots  on  the  limestone  constituents  of  the  soil  ? 

45.  To  demonstrate  the  force  with  which  roots  absorb 
water  from  the  soil,  cut  a  groove  in  the  form  of  a  circle 
about  two  centimeters  in  diameter,  by  means  of  the  edge 
of  a  three-cornered  file,  at  the  large  end  of  a  hen's  egg. 
Carefully   remove   the   shell   within   the   circle,  guarding 
against  puncturing  the  delicate  skin.     File  with  the  flat 
face  of  the  file  at  the  small  end  of  the  egg  until  a  thin  area 
about   four   millimeters   in   diameter   has  been  produced, 
make  a  small  hole  in  the  shell  at  the  thin  place,  and  blow 
out  the  contents  by  means  of  a  glass  tube  drawn  out  in  a 
flame  to  a  fine  point.     In  this  "operation  the  tube  must  not 
entirely  close  the  opening  in  the  shell.     Set  the  egg,  large 
end  down,  in  the  mouth  of  a  wide-mouth  bottle  which  has 
been   filled  with   water,   and  fill  the  egg  with  thin  sirup 
colored  with  an  aniline  dye.     A  test  tube  drawn  out  in  a 
flame  to  a  fine  tube  is  an  excellent  funnel  for  this  purpose. 
Hold  a  piece  of  small  glass  tube,  about  one  meter  long, 
upright  against  the  upper  end  of  the  egg  and   over  the 
hole,  and  fasten  it  firmly  in  position,  and  water  tight,  by 
means  of  melted  sealing  wax.      Keep  the  bottle  filled  with 
water,  and  watch  the  progress  of  the  experiment.     In  ab- 
sorbing water  from  the  bottle  the  artificial  cell  formed  by 
the  egg  and  sirup  acts  practically  in  the  same  manner  as 
the  root  hairs  in  absorbing  water  from  the  soil. 

46.  Make  a  cross  section  of  a  root  of  corn  or  bean  and 
treat  with  phloroglucin  (see  page  387).    The  elements  which 
are  colored   red  are   the  water-conducting  elements  into 
which  the  water  passes  from  the  root  hairs.     They  are  in 
reality    long   tubes,   formed   by   the   fusion   of   elongated 


30  Introduction  to   Botany. 

cells,  end  to  end,  which  extend  continuously  through  the 
stem  into  the  leaves,  where  they  branch  and  help  to  form 
the  veins  and  veinlets.  Make  similar  sections  of  a  root,  not 
more  than  three  millimeters  in  diameter,  of  some  woody 
plant,  and  treat  with  phloroglucin  as  before.  The  ele- 
ments, which  in  this  instance  are  colored  red,  consist  of 
wood  fibers  in  addition  to  the  water-conducting  tubes.  The 
larger  openings  of  the  latter  can  easily  be  seen  by  means 
of  a  simple  lens. 

47.  Make  a  cross  section  of  a  small  sweet  potato,  which 
is  in  reality  a  root,  and  treat  with  the  iodine  solution.    The 
section  is  stained  purple,  because  it  is  filled  with  starch 
which  supplies  with  food  the  young  shoots  that  spring 
adventitiously  from  the  root.     Plant  some  sweet  potatoes 
in  moist  sand  and  keep  in  a  warm  place.     As  the  shoots 
develop,  what  change  is  noticed  in  the  size  of  the  root? 

48.  Make  cross  sections  of  dodder,  which  is  parasitic  on 
balsam,  stinging  nettle,  or  some  other  herbaceous  plant. 
This  material  gives  best  results  if  it  is  taken  in  a  young 
and  tender  condition  and  placed  in  70  jfc  alcohol  for  a  time, 
and  afterwards  preserved  in  equal  parts  of  alcohol,  glycer- 
ine, and  .water.     Or  it  may  be  kept  from  the  first  in  a  2  jfr 
formalin  solution.     Select  a  section  showing  the  penetra- 
tion of  the  roots  of  the  dodder  into  the  host  plant.     Treat 
first  with  phloroglucin  and  then  mount  in  chlor-zinc-iodide 
(see  page  381),  or  mount  in  the  latter  reagent  alone,  and 
examine  with  the  compound  microscope.     An  examination 
with  a  simple  lens  even  will  give  a  fairly  good  idea  of  the 
intimate  relation  between  the  parasite  and  its  host. 

49.  Take    germinating    seeds    of    Indian    corn    whose 
primary  roots  are  about  one  centimeter  long,   and  with 
waterproof  India  ink  make  marks  on  the  roots  one  milli- 
meter apart,  beginning   at   the   apices.      On  other  roots 


Roots.  31 

make  heavy,  continuous  lines  running  their  full  length. 
Place  the  seedlings  in  moist  sawdust,  and  after  a  day 
notice  whether  the  marks  have  separated  at  one  portion 
more  than  at  another,  and  whether  the  continuous  mark 
has  become  broken  at  one  portion  more  than  at  another. 
What  do  these  experiments  teach  as  to  the  regions  of 
greatest  elongation  in  roots? 

50.  Examine  the  roots  of   trumpet  creeper,  which  are 
growing  into  some  support.     Do  they  appear  to  arise  at  a 
definite  place  on  the  stem  ?     Do  they  grow  directly  toward 
the  support,  or  do  they  seem  to  have  been  uncertain  as  to 
the  proper  direction  to  take?     How  deep  do  the  roots  pen- 
etrate into  the  support  ?     If  growing  into  a  tree,  do  the 
roots  seem  to  have  penetrated  to  a  sufficient  depth  to  take 
sap  from  the  tree  ?     The  material  for  this  study  can  be 
secured  at  any  time  during  the  year.     It  is  a  good  plan, 
however,  to  gather  it  during  the  growing  season  and  keep 
it  in  jars  of  2  fy  formalin. 

51.  Early  in  the  spring,  when  the  buds  begin  to  swell, 
cut  off  a  grape  vine  about  six  inches  from  the  ground,  and 
attach  a  long  glass  tube  to  the  stump  by  means  of  a  short 
piece  of  rubber  tube.     Tie  the  glass  tube  to  a  support  so 
that  it  is  held  vertically.     Keep  note  of  the  rapidity  of  the 
rise  of  sap  in  the  tube. 

52.  Cut  off  a  small  branch  of  willow  and  place  it  in  a 
bottle  of  water.     Set  the  bottle  in  a  warm  place  and  keep 
the  water  replenished.     Note  from  time  to  time  whether 
roots  are  forming  in  or  above  the  water,  and  if  so  whether 
they  are  formed  in  definite  order. 

DISCUSSION. 

17.    Functions  of  Roots.     The  roots,  of  plants  have  to 
perform  the  functions  of  fixation,  mechanical  support,  ab- 


Introduction  to  Botany. 


sorption  and  conduction  of  fluids,  and  storage.  In  follow- 
ing the  development  of  the  seedling,  we  have  noticed  that 
its  first  efforts  are  directed  toward  the  formation  of  its  root 
system.  It  would  be  hazardous  for  seedlings  to  develop 
parts  above  the  ground  before  an  anchorage  has  been 
made  in  the  soil,  for  in  that  case  the  young  plant  could 
easily  be  torn  or  washed  from  its  position  by  storms,  and 
death  would  likely  result  from  lack  of  water  if  the  leaves 

were  spread  out  above  the 
ground  before  connection 
had  been  established  with 
the  water  of  the  soil. 

18.  Growth  of  the  Root— 
As  shown  by  Experiments 
41  and  49,  the  root,  elongat- 
ing only  near  the  apex,  is 
directed  downward  by  grav- 
ity. The  delicate  root  apex, 
of  course,  meets  with  obstruc- 
tions, but  it  is  protected  by 
a  cushion  of  cells  known  as 
the  root  cap  (see  Fig.  10). 
Being  in  a  state  of  growth, 

and  longitudinal  section  of  a  Root  Tip.  it    is    quickly    responsive    to 

n,  a  root  hair ;  m,  a  young  lateral  root;  jts    surroundings,    and,   turn- 

/,  the  root  cap.      Tracheal   tubes  are  .              •  j         t_        •                        •  i_ 

shown  near  the  center  in  both  cross  and  ing  aside  when  it  meets  With 

longitudinal  section.  Particles  of  soil  are  obstructions,  it  paSSCS  along 

represented  clinging  to  the  root  hairs.  A                          c 

the  course  of  least  resist- 
ance. While  the  root  is  thus  threading  its  way  among  the 
soil  particles,  hairs  are  being  formed  on  it,  always  a  short 
distance  back  of  the  apex,  keeping  pace  with  it  as  it 
advances  in  growth  and  gradually  dying  off  on  the  older 
portions.  Thus  the  root  hairs,  which  are  the  main  absorb- 


FlG.  10. 

Diagrammatic  representation  of  a  cross 


Roots. 


33 


ing  portions  of  the  root,  are  continually  brought  into  new 
parts  of  the  soil,  where  fresh  supplies  of  materials,  suit- 
able for  forming  the  food  of  the  plant,  are  to  be  obtained. 

19.  Importance  of  Root  Hairs.  —  The  root  hairs  are  organs 
of  much  importance,  since  they  greatly  increase  the  anchor- 
ing strength  of  the  root  and  furnish 

an  increased  surface  for  the  absorp- 
tion of  water  and  other  substances 
from  the  soil.  (See  photomicro- 
graph of  root  and  root  hairs  of  bar- 
ley, Fig.  11.)  It  has  been  estimated 
that  the  hairs  on  corn  roots,  for  in- 
stance, increase  the  absorbing  sur- 
face about  twelve  times.  When 
plants  are  transplanted  during  the 
growing  season,  after  the  leaves 
have  been  formed,  they  are  quite 
certain  to  wilt,  because  the  newer 
rootlets  with  their  root  hairs  are 
broken  off,  even  when  the  greatest 
care  is  exercised.  The  best  time 
to  transplant  is,  therefore,  in  the 
fall,  after  the  leaves  have  dropped  off,  or  in  the  spring, 
before  the  new  growth  begins. 

20.  The  Nature  of  the  Soil. — The  value  of  a  wide  dis- 
tribution of  the  roots  in  the  soil  lies  in  the  fact  that,  aside 
from  the  benefits  of  anchorage,  plants  must  take  from  the 
soil,  wrater  and  certain  other  substances  without  which  they 
could  not  live.     The  soil  is  therefore  a  subject  of  great 
interest  in  connection  with  the  study  of  plants.     There  are 
various  kinds  of  soils,  but  it  may  be  stated  in  general  that 
ordinary  tillable  soil  consists  of  particles  of  rocks  in  va- 
rious degrees  of  disintegration,  intermixed  with  vegetable 


FIG.  ii. 

Photomicrograph  of  a  root  of 
Barley,  showing  root  hairs 
forming  near  the  apex  and 
dying  away  behind.  X  3. 


34  Introduction  to  Botany. 

and  animal  remains  which,  on  account  of  the  large  percent- 
age of  carbon  contained  in  them,  impart  to  the  soil  its 
dark  color. 

The  process  of  soil  formation  from  the  disintegration  of 
rocks  can  be  seen  to  advantage  in  any  abandoned  quarry. 
The  newly  uncovered  rocks  are  hard  throughout,  but  those 
which  have  lain  for  some  time  exposed  to  the  weather 
become  so  soft  at  the  surface  that  they  may  easily  be 
scratched,  or  a  considerable  amount  of  material  may  be 
scraped  from  them  by  the  finger  nail.  After  longer  expos- 
ure, and  particularly  after  the  water  imbibed  by  them  has 
been  frozen,  the  rocks  begin  to  crumblaninto  pieces  of  vari- 
ous degrees  of  fineness. 

In  whatever  way  rocks  become  broken  down  —  whether 
by  the  solvent  effect  of  water,  the  expansive  force  of  freez- 
ing water,  or  the  beating  of  storms ;  by  abrasion  when 
carried  along  by  torrents,  or  when  hurled  to  and  fro  by 
the  surf,  or  when  ground  as  in  a  mill  by  glaciers  —  the  ac- 
cumulated particles  in  time  form  a  soil  for  the  growth  of 
plants.  But  long  before  the  new  soil  is  occupied  by  the 
higher  plants  it  becomes  the  home  of  myriads  of  micro- 
scopic forms  whose  remains  contribute  to  its  richness  and 
put  it  in  a  physical  condition  better  adapted  to  the  recep- 
tion of  the  larger  and  more  exacting  plants. 

21.  Soil  a  Reservoir  for  Water.  —  The  capacity  of  the  soil 
to  hold  water  is  dependent  on  the  fineness  of  its  particles ; 
for  the  finer  the  particles,  the  greater  the  number  of  small 
capillary  spaces  and  the  larger  the  surface  exposed  for 
holding  water  by  adhesion.  To  take  a  concrete  example: 
A  cubic  foot  of  round  soil  particles  having  a  diameter  of 
one  inch  would  expose  a  total  surface  of  37.7  square  feet, 
while  a  cubic  foot  of  such  particles  one  one-thousandth  of 
an  inch  in  diameter  would  present  an  aggregate  surface 


r 


Roots.  \  35 

-y  (  ' 

of  37,700  square,  feet.  The  greater  surface  presented  by 
the  smaller  particles  is  of  further  advantage  in  giving  the 
water  increased  opportunity  to  dissolve  out  from  them  cer- 
tain substances  necessary  to  the  food  of  plants. 

22.  Action  of  Root  Hairs.  —  The  root  hairs  place  them- 
selves in  close  contact  with  the  soil  particles,  and  conform 
to  their  irregularities  of  surface 
so  completely  as  to  embed  and 
hold  them  fast.  This  accounts 
for  the  difficulty  of  washing  away 
the  soil  from  the  roots  without 
breaking  off  the  hairs.  The  close 
relation  of  the  root  hairs  to  the 
soil  is  of  great  importance,  for 
long  after  the  capillary  spaces 
have  been  emptied  of  their  water 
by  evaporation,  the  soil  particles 
still  retain  a  film  of  water  about 
them  from  which  the  root  hairs 
are  able  to  draw  supplies  for  the 
plant,  even  when  the  soil  ap- 
pears dry. 

A  better  comprehension  of  the 
absorptive  action  of  the  root  hairs 
will  be  obtained  after  an  exami- 
nation of  their  structure  and  the 
circumstances  governing  their  ac- 
tion. They  are  really  greatly  elongated  outer  or  epidermal 
cells  of  the  roots  (see  Figs.  1 1  and  12).  Their  outer  wall,  a 
(Fig.  12,  A  and  B\  is  quite  thin,  and  composed  of  cellulose, 
a  substance  readily  permeable  to  water.  Within  the  cell 
wall  is  the  live  part  of  the  cell  known  as  the  protoplast 
(all  of  the  granular  part  in  A\  consisting  of  the  outer  lin- 


FlG.  12. 

A,  diagrammatic  representation 
of  a  Root  Hair;  B,  a  more 
highly  magnified  detail,  a  being 
the  outer  cellulose  wall,  b  the 
plasma  membrane,  and  c  the 
cytoplasm,  d  is  the  nucleus 
suspended  in  the  cytoplasm. 


36  Introduction  to  Botany. 

ing  membrane,  b,  called  the  plasma  membrane,  a  specialized 
part  of  the  cytoplasm  ;  the  cytoplasm,  c  ;  and  the  nucleus,  d. 
Plasma  membrane,  cytoplasm,  and  nucleus  are  alive,  while 
the  cell  sap,  which  occupies  the  remainder  of  the  cell 
cavity  (all  of  the  clear  space  within  A\  and  the  cell  wall 
are  not  endowed  with  life.  The  plasma  membrane  is 
readily  permeable  to  water,  but  not  to  all  substances 
which  the  water  may  contain  in  solution.  Its  chief  ser- 
vic,e  consists,  not  so  much  in  keeping  certain  substances 
from  entering  the  plant,  as  in  prohibiting  the  valuable 
cell  sap  and  portions  of  the  living  body  of  the  cell  from 
passing  out  and  becoming  lost  to  the  plant.  Thus,  while 
vast  amounts  of  water  with  substances  in  solution  pass 
into  the  plant  through  the  root  hairs,  only  very  small 
quantities  of  materials,  useful  in  rendering  soluble  those 
substances  which  the  plant  needs,  are  permitted  to  pass 
out  by  the  same  channels. 

23.  The  Process  of  Absorption.  —  The  process  of  the 
passage  into  the  root  hairs  of  the  substances  dissolved  in 
the  water  of  the  soil  is  known  as  diffusion.  The  initial 
force  which  causes  this  probably  results  from  the  energy 
of  motion  of  the  molecules  and  ions  of  the  diffusing 
substance.  Those  molecules  and  ions  which  possess  the 
greatest  energy  of  motion,  or  whose  size  and  shape  best 
conform  to  the  intermolecular  spaces  of  the  membrane, 
will  traverse  the  membrane  most  rapidly.  When  the 
molecules  and  ions  of  a  substance  in  solution  are  in  equal 
concentration,  that  is,  are  in  equal  number  per  unit  of  vol- 
ume on  both  sides  of  the  membrane,  and  their  temperature 
is  the  same,  the  number  of  them  passing  the  membrane  in 
both  directions  per  unit  of  time  will  be  the  same.  This 
is  a  state  of  equilibrium  which  can  only  occur  between  the 
soil  and  the  root  hairs  in  the  case  of  those  substances  which 


Roots.  37 

are  not  being  withdrawn  from  solution  within  the  plant,  or 
are  not  being  used  by  the  plant  in  the  manufacture  of  new 
compounds.  The  more  a  substance  is  being  employed  or 
transformed  by  a  plant,  so  that  its  concentration  is  continu- 
ally diminished,  the  more  it  will  enter  from  without ;  in 
this  way  the  supply  is  adjusted  to  the  demand. 

If,  on  the  other  hand,  a  substance  which  is  able  to  pass 
the  plasma  membrane  is  not  being  transformed  by  the 
plant,  it  cannot  continue  to  enter  after  the  concentration 
of  its  molecules  and  ions  within  the  plant  is  equal  to  that 
in  the  soil  water;  in  this  way  useless  materials  are  kept 
from  accumulating.  This  is  true  of  the  substances  in  solu- 
tion, but  the  solvent,  which  in  this  case  is  water,  passes 
most  rapidly  from  the  region  of  less  to  that  of  greater 
concentration  (see  Experiment  45).  The  passage  of  water 
through  membranes  from  regions  of  lower  to  those  of 
higher  concentration  is  known  as  osmosis.  The  cell  sap 
of  the  root  hairs  is  of  greater  concentration  than  the  soil 
water;  and  since  this  condition  is  maintained  by  evapo- 
ration from  the  leaves  and  other  above-ground  parts,  and 
by  the  employment  of  some  of  the  water  in  the  manufac- 
ture of  plant  food,  the  water  continues  to  enter  the  plant 
from  the  soil.  If  the  water  is  abundant,  it  may  enter  the 
plant  even  faster  than  it  is  evaporated  or  used,  in  which 
case  the  plant  cells  become  stretched  and  turgid.  In  this 
way  rigidity  is  given  to  herbaceous  stems  and  leaves.  But 
when  the  water  in  the  soil  runs  low,  evaporation  may  be  in 
excess  of  its  movement  into  the  plant,  and  wilting  results. 

24.  Importance  of  Water. — Water,  which  is  taken  by 
land  plants  almost  exclusively  from  the  soil,  is  the  solvent 
and  vehicle  of  transport  for  all  substances  which  enter  the 
plant,  and  for  those  compounds  as  well  which  are  manu- 
factured within  the  plant ;  it  contributes  its  own  substance 


Introduction  to  Botany. 


for  the  manufacture  of  plant  food,  and  it  further  serves 
the  plant  in  affording  strength  and  rigidity  to  the  tender 
herbaceous  parts. 

25.   Elements  Necessary  to  Plants. — There  are  certain 
chemical  elements  necessary  to  the  nutrition  of    plants, 

which  must  be  taken 
from  the  soil  particles ; 
these  are  calcium,  mag- 
nesium, potassium,  sul- 
phur, phosphorus,  and 
iron.  Nitrogen  is  taken 
in  part  from  the  com- 
pounds of  nitrogen  in 
the -soil,  and  in  part  in- 
directly from  the  free 
nitrogen  of  the  atmos- 
phere by  means  of  mi- 
croscopic organisms 
which  reside  chiefly  in 
the  root  tubercles  of 
leguminous  plants  (see 
Fig.  13).  Were  it  not 
for  the  fact  that  these 
elements,  for  the  most 
part,  are  in  the  form  of 
compounds  insoluble  in 
water,  they  would  soon  be  washed  away  by  the  percolating 
water  after  heavy  rains.  They  are,  however,  slowly  rendered 
soluble  by  acids  excreted  by  the  root  hairs  (see  Experiment 
44),  by  carbon  dioxide  dissolved  in  the  soil  water,  and  by 
the  oxygen  of  the  soil  atmosphere.  It  must  be  remembered 
that  there  are  no  openings  in  the  root  hairs,  and  only  sub- 
stances in  solution  in  water  can  be  absorbed  by  them. 


FIG.  13. 

D,  root  of  a  leguminous  plant  bearing  Tuber- 
cles; E,  a  cell  from  a  tubercle  containing 
bacteria,  highly  magnified ;  F,  some  of  the 
bacteria  more  highly  magnified;  .G,  a  cell 
from  a  tubercle  after  the  bacteria  have,  in 
part,  evidently  been  absorbed  by  the  plant. 
After  FRANK. 


Roots.  39 

26.  Free  Nitrogen    made  Available.  —  Although   about 
seventy-nine  parts  in  one  hundred  of  the  atmosphere  con- 
sist of  free  nitrogen,  plants,  with  the  exception  of  certain 
microscopic  forms,  are  not  able  to  use  it  for  food  until  it 
has  been  combined  with  other  elements  to  form  some  solu- 
ble compound,  such  as  nitrates  and  ammonia.     These  are 
obtained  largely  from  the  decomposing  remains  of  plants 
and  animals.     It  has  long  been  known  that  clover,  when 
plowed  under,  leaves  the  soil   much   richer   in    nitrogen, 
and  the  reason  for  this  is  now  well  understood.     There 
are  bacteria  residing  in  the  tubercles  of  the  clover  roots 
(see  Fig.   13),  and  they   in    some   way  combine  the  free 
nitrogen  of  the  atmosphere  with  the  other  necessary  food 
constituents  provided  by  the  clover  plant,  and  use.  the  sub- 
stances thus  formed  as  food.     After  a  time  the  bacteria 
become  disintegrated,  and  are  apparently  absorbed  by  the 
clover,"  which,  in  this  roundabout  way,  obtains  the  nitrogen 
after  it  has  Been  combined  with  other  substances  to  form 
proteids.     Finally,  the  clover  decays  and  yields  its  com- 
bined nitrogen  to  the  soil.     By  this  remarkable  cooperation 
of  two  widely  different  kinds  of  plant  life  the  free  nitrogen 
of  the  atmosphere  is  made  available  to  all  kinds  of  plants. 

27.  Extent  of  Roots.  —  The  roots  with  their  rootlets  and 
root  hairs  form  a  dense  plexus  threading  the  soil  in  all  direc- 
tions.    Being  buried  in  the  soil,  their  great  extent  is  not 
easily  apprehended.     It  has  been  estimated  that  if  all  the 
roots  and  rootlets  of  a  single  corn  plant  grown  under  good 
field  conditions  were  placed  end  to  end  they  would  cover* a 
linear  mile.     The  roots  of  some  plants  extend  to  great 
depths,  and  these  plants  are  thus  able  to  obtain  water  and 
continue  fresh  and  green  after  the  surface  soil  has  become 
dry  and   plants  with    shallow  roots  have  withered  away. 
The  roots  of  alfalfa,  for  instance,  sometimes  penetrate  the 


4-O  Introduction  to   Botany. 

soil  to  a  depth  of  from  ten  to  twenty  feet,  this  habit  mak- 
ing it  valuable  for  hay  and  pasturage  in  regions  of  scanty 
rainfall. 

28.  Path  of  Absorbed  Substances.  —  The  water  aiid  sub- 
stances in  solution  pass  from  the  root  hairs  toward  the 
center  of  the  root,  where  they  enter  tubes  (see  Figs.  10  and 
42)  which  conduct  them  through  the  stem  into  the  leaves. 
The  osmotic  force  in  the  root  hairs  is  sufficient  to  lift  the 
water  in  the  stem  to  a  considerable  height  (compare  Ex- 
periment 51),  but  this  force  is  not  of  itself  sufficient  to 
carry  the  water  up  rapidly  enough  to  supply  the  evapora- 
tion from  the  leaves,  nor  high  enough  to  reach  the  tops  of 

tall  trees.  Figure  10  shows 
the  relation  between  the  root 
hairs  and  the  water-conducting 
tubes  (called  tracheal  tubes  be- 
FIG.  14.  cause  of  their  resemblance  in 

floating  water  plant.   The  appearance  to  tlie  trachea  or. 

slender  roots,  destitute  of  root  hairs, 


grow  down  in  the  water.    Slightly 

magnified.  29.  Roots  of  Water  Plants.  — 

The  roots  of  water  plants  are 

much  less  extensive  than  those  of  land  plants.  In  the 
case  of  such  plants  as  Lemna  and  Spirodcla  (see  Fig.  14), 
which  float  upon  the  water,  the  roots  are  few,  short,  and 
unbranched,  and  destitute  of  hairs.  Such  plants  do  not 
need  an  elaborate  root  system,  since  water  and  food  sub- 
stances dissolved  in  it  are  available  without  stint  at  all 
times. 

30.  Roots  of  Parasitic  Plants.  —  Some  plants  have  de- 
veloped parasitic  habits  and  attach  themselves  to  other 
plants  by  means  of  their  roots,  having  no  direct  connection 
with  the  soil,  but  depending  upon  their  host  plant  for  the 
water  and  other  necessary  food  materials.  If  the  parasite 


Roots. 


has  no  green  leaves,  as  in  the  case  of  dodder  (see  Fig.  15), 
it  must  depend  upon  its  host  for  all  kinds  of  food  mate- 
rials,—  for  the  starches,  sugars,  oils,  and  proteids  manufac- 
tured by  its  host.  It  is,  in  other  words,  a  complete 
parasite.  But  if,  as  in  the  case  of  the  mistletoe,  it  has 
green  leaves  of  its  own,  it  is  entirely  dependent  on  its  host 
for  the  water  and  dis- 
solved soil  materials 
only,  and  is  then  but 
partly  parasitic. 

31.  Roots  of  Air  Plants. 
—  The   aerial  roots    of 
some    tropical    orchids 
and  of  other  aerial  plants 
(see  Fig.  16)  do  not  be- 
come embedded  in  a  sub- 
stratum, but  grow  free  in 
the  air,  and  they  must, 
therefore,    be    able    to 
absorb  rapidly  the  water 

which  falls  or  gathers  on  them  from  the  rain  or  dew. 
To  accomplish  this  the  outer  layers  of  the  cells  of  the 
roots  are  empty  and  their  walls  are  perforated  by  minute 
openings  through  which  the  water  can  be  drawn  by  capil- 
larity. It  may  be  that  the  water  vapor  of  the  atmosphere 
is  condensed  within  these  cells,  but  experiments  on  this 
subject  have  given  contradictory  results. 

32.  Prop  Roots.  —  The  prop  roots  growing  at  the  basal 
nodes  of  Indian  corn,  and  the  famous  prop  roots  of  the 
banyan  tree,  grow  downward  to  or  into  the  soil.     Supported 
in  this  way,  the  banyan  tree  is  able  to  spread  its  branches 
over   an    area   so    large   as   to   give  shelter  to  an  entire 
.village. 


FIG.  15. 


A,  Cuscuta  Europaea,  or  Dodder,  twining  about 
and  parasitic  on  a  hop  vine  and  bearing  a 
cluster  of  small  flowers. 

B,  diagrammatic  drawing  of  a  cross  section  of 
a  hop  vine  through  the  plane  where  the  roots 
of  the  dodder  enter  it  and  penetrate  to  its 
vascular  bundles.     X  fS.    After  K.ERNER. 


Introduction  to   Botany, 


FIG.  16. 

Aerophytes  growing  on  the  trunk  and  branches  of  a  tree.  Aerial  roots  seen 
pendent  from  the  branch  on  the  left.  Drawn  from  data  in  Schimper's 
Pflanzengeographie . 


Roots. 


43 


33.  Clinging  Roots.  —  The  roots  growing  on  the  stems 
of  the  poison  ivy  and  trumpet  creeper  (Fig.   17),  for  in- 
stance, do  not  serve  an  absorbing  function,  but  are  merely 
employed  in  holding  the  slender  stems  upright  against  a 
support.     If  these  plants  are  growing  near  a  tree  or  wall 
they  find  themselves  shaded  on  one  side,  and  their  roots 
grow  away  from  the  side  of  greater 

illumination  and  toward  the  object 
which  is  shading  them ;  in  this  way 
they  are  quite  certain  to  find  a  suit- 
able support. 

34.  The  Various  Directive  Forces. — 
Thus  we  see  that  roots  have  quite 
diverse  functions  to  perform  and  that 
they  show  a  marvelous  capacity  for 
employing   various    forces    to    direct 
them  in  their  growth.     If  they  are 
to  grow  into  the  soil,  gravity  is  chosen 
as  a  guide ;  if  into  the  body  of  some 
host,  as  in  the  case  of  dodder,  the 
stimulus    of   contact   is    selected ;    if 
toward  some  object  of  support,  either 

light  or  gravity  is  chosen,  as  is  most  practicable.  Even  to 
any  given  force  the  various  parts  of  the  root  system  may 
react  differently;  the  main  roots  growing  in  the  soil  are 
directed  more  or  less  downward ;  the  lateral  roots  spring- 
ing from  these  make  greater  or  less  angles  with  the  line 
of  gravity;  while  the  ultimate  branches  may  grow  in  any 
direction,  apparently  without  respect  to  gravity.  In  this 
way  all  parts  of  the  soil  within  the  range  of  the  roots  are 
fully  occupied,  which  would  not  be  the  case  if  the  entire 
root  system  were  impelled  by  gravity  in  one  direction.  The 
water  in  the  soil,  also,  has  a  directive  influence  on  the 


FIG.  17. 

Portion  of  a  stem  of  the 
Trumpet  Creeper,  show- 
ing its  clinging  roots. 


44 


Introduction  to   Botany. 


growth  of  the  roots ;  if  the  water  is  distributed  evenly,  the 
roots  develop  evenly  on  all  sides,  but  if  the  conditions  are 
otherwise  the  roots  tend  to  follow  the  direction  of  the 
greater  water  supply. 

35.  Adventitious  Roots.  —  We  have  noticed  in  the  growth 
of  seedlings  that  the  first  rootlets  spring  from  the  primary 

root  at  definite  angles  of  di- 
vergence, but  that  on  the  stems 
of  ivy  and  Cuscuta  their  places 
of  origin  are  indefinite,  —  in 
other  words,  these  roots  seem 
to  arise  adventitiously.  When 
willow  stems  are  cut  off  and 
placed  in  water,  roots  are 
formed  in  the  same  manner 
not  far  above  the  cut  surface. 

Showing  the  method  of  Layering.    A  Xhe    ability  of    plants   to   form 

branch  is  bent  and  pegged  down  , 

and  covered  with  soil.   After  adven-  adventitious  TOOtS  IS  employed 

titious   roots   have   formed   on  the  fry    horticulturists    and    florists 
branch  it  is  severed  from  its  parent 

stock.   After  BARRY.  in  the    propagation   of   many 

kinds  of  plants  by  the  pro- 
cesses known  as  layering  and  cuttage.  In  this  way  may 
be  propagated  currants,  gooseberries,  raspberries,  grapes, 
roses,  azaleas,  fuchsias,  etc.  (See  Fig.  18.) 

36.  Roots  Defined.  —  Although  roots  are  called  upon  to 
perform  various  functions,  and  may  be  modified  in  form 
accordingly,  they  still  have  certain  characteristics  which 
distinguish  them  from  other  plant  members.     They  are 
members  of  the  plant  body  of  indefinite  elongation,  pro- 
tected by  a  root-cap ;  and  they  never  directly  bear  leaves, 
although  capable  of  producing  adventitious  buds. 


FlG- l8- 


CHAPTER   IV. 

BUDS  AND  STEMS. 

PROVIDING   MATERIALS. 

Most  of  the  material  required  in  the  study  of  buds  and  stems  can  be 
procured  out  of  doors  at  any  time  before  growth  begins  in  the  spring. 
If  the  study  is  to  be  taken  up  later  in  the  season,  twigs  of  horse  chest- 
nut, cottonwood,  and  lilac  with  winter  buds  should  be  secured  and  kept 
in  2%  formalin  until  needed.  In  those  schools  where  the  study  of 
botany  is  begun  immediately  after  the  Christmas  vacation,  strong 
shoots  of  the  above  plants  should  be  cut  off  and  placed  in  jars  of  water 
at  the  beginning  of  the  term,  and  kept  in  a  warm  place,  in  order  that 
their  buds  may  be  unfolded  by  the  time  the  study  of  buds  in  their  win- 
ter condition  has  been  completed.  The  twigs  may  be  crowded  into  the 
jars  quite  closely,  and  there  should  be  several  twigs  of  each  kind  for 
every  student.  The  water  in  the  jars  should  be  frequently  changed. 

If  Aristolochia  is  not  at  hand,  it  can  be  obtained  of  dealers  in  botani- 
cal supplies.1  Branches  of  Tilia  (linden)  can  be  used  to  good  advan- 
tage for  sectioning  if  Aristolochia  cannot  be  obtained,  and  branches  of 
elm  might  be  used,  although  less  advantageously.  Aristolochia,  how- 
ever, is  the  best  for  this  study.  These  branches  and  small  stems  of 
Indian  corn  should  be  taken  during  the  growing  season  and  placed  for  a 
week  or  so  in  70%  alcohol,  and  then  kept  in  equal  parts  of  alcohol, 
glycerine,  and  water  until  needed.  This  method  of  treatment  makes  it 
easier  to  cut  good  sections. 

OBSERVATIONS. 

53.  Make  drawings  of  a  twig  of  horse  chestnut  in  its 
winter  condition,  showing  the  relative  size  and  position  of 
all  exterior  structures.  Where  did  last  year's  leaves  grow 
on  the  twig  ? 

1  Cambridge  Botanical  Supply  Co.,  Cambridge,  Mass. 
45 


46  Introduction  to   Botany. 

54.  Make  drawings,  on  a  larger  scale,  of  a  terminal  bud, 
a  lateral  bud,  and  any  structures  related  to  them.     What 
is  the  relation  as  to  position  between  the  leaves  and  buds 
of  the  twig  ? 

55.  Select  one  of  the  largest  buds,  and  pick  off  the  bud 
scales  carefully,  so  as  not  to  injure  them.     Arrange  them 
in  separate  groups  in  the  order  in  which  they  were  removed, 
each  group  being  composed  of  the  scales  which  encircle 
the  stem  once  in  the  successive  spirals,  or  whorls.     Draw 
a  typical  scale  from  each  of  the  groups.     When  the  scales 
are  all  removed,  draw  the  inner  structures  which  were  pro- 
tected by  them  (scale,   x  5);   first,  as  they  stand  in  their 
natural  position  on  the  stem,  and  second,  when  removed 
and  laid  out  for  examination  separately.     If  the  parts  are 
folded  together  make  a  drawing  to  show  the  manner  of 
folding,  and  then  spread  one  of  them  out  and  draw  in  the 
expanded  position.     Use  the  lens  for  this  work,  and  draw 
in  the  details  which  can  be  seen  with  it. 

56.  Make  cross  sections  of  a  bud,  beginning  near  the 
apex  and  sectioning  in  successively  lower  planes  until  the 
parts  protected  by  the  scales  are  seen  to  best  advantage, 
and  then  clraw  to  the  scale  x  2.5.     Identify  the  different 
parts  of  the  sections  by  the  aid  of  the  dissections  already 
made. 

57.  Pay  particular  attention  to  the  protection  afforded 
the  tender  inner  parts  of  the  bud  by  means  of  the  scales 
or   other   structures  or   devices.      The    inner  parts    need 
protection  'against  drying,  sudden  freezing  and  thawing, 
attacks  of  parasites  of  various  kinds,  and  mechanical  in- 
juries due  to  the  beating  of    storms  and  abrasion  from 
other  causes.     In  what  ways  are  these  different   sources 
of  danger  guarded  against  ? 

58.  Make  a  median  longitudinal  section  through  one  of 


Buds  and  Stems.  47 

the  largest  buds,  and  draw  the  cut  surface.  The  drawing 
should  show  the  outline  of  all  the  parts  with  perfect  clear- 
ness. Do  not  make  any  lines  which  have  no  distinct 
significance. 

59.  What  portion  of  this  twig  was  formed  last  year? 
What  portion  was  formed  the  year  before  ?     Is  there  any 
portion  of  the  coming  season's  shoot  present  in  this  twig  ? 
Label  the  drawing  of  the  twig  according  to  the  different 
years'  growth,  and  determine  by  cross  sections  whether 
there  is  any  relation  between  the  internal  structure  and  the 
age  of  the  parts  of  the  twig. 

60.  Make  drawings  of  buds  in  different  stages  of  unfold- 
ing so  that  the  following  questions  may  be  answered  by 
reference  to  the  drawings :    What  changes    do   the   bud 
scales  undergo  ?     What  finally  becomes  of  the  bud  scales  ? 
Do  the  bud  scales  in  any  way  leave  their  impress  upon 
the  twig?     What  changes  do  the  inner  parts  of  the  bud 
undergo  ?     Do  the  parts  increase  in  size  ?  in  number  ?     Do 
they  change  materially  in  form  ?     Are  their  relative  posi- 
tions changed  ?     Are  any  new  parts  produced,  or  does  the 
unfolding  of  the  bud  consist  simply  in  changes  in  parts 
already  present  ? 

6 1.  Turn  back  to  twigs  in  winter  condition  and  deter- 
mine the  location  of  the  bud  scales  of  last  year,  and  of  the 
year  before  that,  etc.,  and  see  that  your  drawing  takes 
proper  account  of  them. 

62.  Count   the   leaf    scars   belonging   to   the   different 
years'  growth  to  determine  whether  the  number  of  leaves 
produced  each  year  is  the  same. 

63.  Determine  the  number  of  vertical  rows  of  leaf  scars, 
and  the  angular  divergence  of  the  leaves  on  various  twigs, 
selecting  those  which  have  made  a  vigorous  growth  and 
are  straight  and   untwisted.     A  good  way  to  determine 


48  introduction  to   Botany. 

the  number  of  vertical  rows  is  to  stick  pins  or  dissecting 
needles  into  each  leaf  scar  perpendicular  to  the  tangent  at 
that  point,  passing  spirally  up  the  stem,  omitting  none  of 
the  scars,  until  the  scar  is  reached  which  stands  immedi- 
ately above  the  initial  scar,  that  is,  the  one  with  which  the 
start  was  made.  When  the  twig  is  now  held  in  front  of 
the  observer,  parallel  to  the  line  of  vision,  the  number  of 
vertical  rows  of  leaf  scars  may  easily  be  counted  and  the 
angular  divergence  of  the  rows  determined.  The  angular 
divergence  of  a  leaf  from  the  one  next  above  or  below  it  is 
now  to  be  determined. 

Suppose  that  in  counting  the  scars  it  is  found  that  in 
passing  once  around  the  stem  the  fifth  scar  is  immediately 
above  the  initial  scar;  then  it  is  plain  that  the  angular 
divergence  of  the  leaves  from  each  other  is  one  fifth  of 
360°,  or  72°.  But  suppose  the  five  leaves  are  distributed 
over  two  turns  of  the  stem  ;  then  it  is  evident  that  they  are 
twice  as  far  apart  as  in  the  first  case,  that  is,  their  angular 
divergence  is  now  twice  72°,  or  144°.  If  examples  of  this 
sort  were  multiplied,  it  would  be  seen  that  the  angular 
divergence  of  the  leaves  would  be  that  fraction  of  360° 
whose  numerator  is  the  number  of  times  the  circumference 
of  the  stem  is  passed  over,  and  whose  denominator  is  the 
number  of  intervals  traversed  in  passing  spirally  from  the 
initial  scar  to  the  one  directly  above  it.  Of  what  use  is  a 
definite  angular  divergence  of  the  leaves  ? 

64.  Study  in  like  manner  cottonwood  and  lilac. 

65.  Make  thin  cross  sections  of  a  one-year-old  stem  of 
Aristolochia,  and  treat  with  phloroglucin   and   chlor-zinc- 
iodide,  or  double   stain  with   cyanin    and   erythrosin  (see 
page  384).     Examine  with  a  simple  lens  or  with  the  low 
power  of  the  compound  microscope.  ^  On   the  outside  is 
the  epidermis,  a  (Fig.  19).     Within  this  is  a  zone  of  tissues 


Buds  and  Stems. 


49 


known  as  the  primary  cortex,  extending  to  and  including 
the  row  of  cells,  b,  which  is  termed  the  starcJi  sheath  or 
endodermis.  The  groups  of  tissues  within  the  endodermis 
make  up  the  central  cylinder  or  stele.  The  groups  of  tis- 
sues, d,  which  are  disposed  in  the  form  of  an  interrupted 
concentric  zone,  are  known  as  the  vascular  bundles.  The 
tissues  between  the  en- 
dodermis and  the  vas- 
cular bundles  constitute 
the  pericycle,  c.  The 
tissue  surrounded  by 
the  vascular  bundles  is 
termed  the  pith,  e.  The 
tissue  connecting  the 
pith  with  the  pericycle, 
and  accordingly  run- 
ning radially  between 
the  vascular  bundles,  is 
termed  the  medullary 
rays,  f. 

Cross  section  of  a  one-year-old  stem  of  Aristolo- 

Aristolochia  which  are  chia.  a,  epidermis;  b,  endodermis;  c,  peri- 
treated  with  nhloroHu  c>cle;  d>  vascular  bundle:  ',  Pith=  ff>  cam- 

r°Sm  bium ;  A.  sclerenchyma  ring  of  the  pericycle; 

Cin     and      chlor-zillC-          «, collenchyma ;  /  medullary  ray. 

iodide,  it  is  seen  that  the 

vascular  bundles  consist  of  two  distinct  parts  —  an  inner 
part  which  is  colored  red  by  the  phloroglucin,  and  possesses 
relatively  large  openings,  and  an  outer  part  which  is  col- 
ored purple  by  the  chlor-zinc-iodide,  and  whose  cells  are 
relatively  small.  The  inner  part,  which  is  known  as  the 
xylem,  is  the  water-conducting  part  of  the  bundle;  while 
the  outer  part,  termed  the  pJtloem,  is  the  food-conducting 
part.  The  small,  brick-shaped,  thin-walled  cells,  g,  be- 


FiG.  19. 


50  Introduction  to  Botany. 

tween  the  phloem  and  xylem  are  the  cambium  cells,  which, 
during  the  growing  season,  rapidly  divide  and  form  new 
cells  that  finally  become  altered  into  the  tubes,  etc.,  of  the 
xylem  and  phloem.  As  the  stems  grow  older,  cambium 
is  formed  between  the  bundles,  and  thus  is  produced  a 
complete  ring  of  delicate  cells  which  permits  the  bark  to 
be  separated  readily  from  the  wood. 

The  bark  is  composed  of  all  the  tissues  outside  the  cam- 
bium ring,  so  that  when  the  bark  is  stripped  off  the 
phloem  portion  of  the  vascular  bundles  goes  with  it  (see 
Fig.  21).  Turning  again  to  the  section  of  Aristolochia, 
one  sees  that  a  portion  of  the  pericycle  (//,  known  as  the 
sclerenchyma  ring)  is  composed  of  cells  which  are  thick- 
walled  and  lignified,  as  indicated  by  their  being  stained 
red  by  phloroglucin,  or  blue  by  the  cyanin.  A  longitudinal 
section  would  show  that  these  cells  are  elongated  in  the 
direction  of  the  long  axis  of  the  stem  and  are  closely 
bound  together,  being  thus  well  adapted  to  give  strength 
to  the  stem.  If  the  section  is  carefully  studied,  it  will  be 
seen  that  these  different  tissues  are  not  separated  from 
each  other  by  lines,  such  as  the  beginner  might  be  tempted 
to  use  in  drawing  them,  but  that  they  owe  their  demarca- 
tion to  the  fact  that  the  cells  composing  them  differ  in 
form  and  size,  in  the  character  of  their  contents,  and  in 
the  thickness  and  kind  of  their  walls. 

The  tissues  are  adapted  to  perform  various  functions 
by  their  different  characters  and  relative  positions.  The 
epidermis  has  an  outer  wall  which  is  infiltrated  with  waxy 
substances  and  is  thus  adapted  to  prevent  the  inner  tissues. 
from  drying  up ;  the  epidermis  has,  therefore,  a  protective 
function.  The  thick-walled  cells  of  the  outer  part  of  the 
primary  cortex  (z,  known  as  the  collenchyma)  are  chiefly 
for  giving  strength.  The  inner  cells  of  the  primary  cortex 


Buds  and  Stems.  51 

are  thin-walled,  and  the  walls  are  made  of  cellulose,  a  sub- 
stance which  is  easily  permeable  to  water  and  substances 
in  solution.  These  cells  are  therefore  fitted  for  the  storage 
and  slow  conduction  of  materials ;  and  since  they  lie  near 
the  periphery  and  are  accessible  to  light,  they  contain  the 
same  kind  of  green  chloroplasts  which  reside  in  the  leaves, 
and  use  the  energy  of  the  light  in  manufacturing  food 
materials  (see  page  87).  The  outer  portion  of  the  peri- 
cycle,  on  account  of  the  thickness  and  lignification  of  its 
cell  walls  and  of  the  elongation  and  close  union  of  its 
cells,  is  adapted  to  give  strength  and  rigidity  to  the  stem. 
The  inner  portion  of  the  pericycle,  having  thin,  cellulose 
walls,  is  adapted  to  the  storage  and  slow  conduction  of 
materials  in  solution.  The  phloem  portion  of  the  vascular 
bundles  probably  carries  proteid  and  other  food  materials 
rapidly  up  and  down  the  stem  as  needed,  being  fitted  for 
this  purpose  by  its  long,  thin-walled,  tubular  cells,  which 
are  separated  longitudinally  by  partitions  having  perfora- 
tions, through  which  materials  may  readily  pass.  The 
xylem  portion  of  the  bundles  carries  water  upward  from 
the  roots  through  its  tracheal  tubes,  while  the  wood  fibers 
associated  with  the  tracheal  tubes  contribute  to  the  strength 
and  hardness  of  the  stem.  When  we  consider  the  vascular 
bundle  as  a  whole  we  see  that  its  conductive  function  is 
preeminent.  The  medullary  rays  carry  materials  radially 
to  and  from  the  bark  and  pith  and  to  and  from  the  vas- 
cular bundles.  The  pith  may,  in  its  young  state,  conduct 
materials  up  and  down  as  needed,  but  as  it  gets  older  it 
dies  and  contains  air  only,  or  it  may  break  down  entirely. 

Study  also  cross  sections  of  an  Aristolochia  stem  which  is 
several  years  old  and  note  the  changes  which  have  taken 
place  in  the  different  tissues  since  the  first  year. 

66.    Make  a  diagrammatic  drawing  of  the  different  zones 


Introduction  to  Botany. 


of  tissues  seen  in  the  cross  section  of  the  stem,  simply  out- 
lining them  in  right  position  and  proportion,  and  with  the 
colored  pencils  give  each  part  having  a  distinct  function  a 
color  of  its  own.  For  instance,  color  the  epidermis  blue, 
the  thick-walled  cells  of  the  primary  cortex  red,  and  its 
thin-walled  cells  green,  the  strengthening  ring  of  the  peri- 
cycle  red,  the  inner  portion 
of  the  pericycle,  medullary 
rays,  and  pith  yellow,  the 
phloem  purple,  the  xylem 
orange,  and  leave  the  cam- 
bium uncolored.  Run  dotted 
lines  from  the  different  parts 
and  at  the  end  of  each  line 
write  the  name  and  function 
of  the  part. 

67.  Make  sections  of  the 
stem  of  Indian  corn  where 
it  is  about  one  centimeter  in 
diameter,  and  treat  as  di- 
rected for  Aristolochia.  Here 
the  bundles  are  scattered 
promiscuously  throughout 

the  stem,  and  there  is  no  distinction  into  pith  and  medul- 
lary rays  (Fig.  20).  The  stem  is  given  strength  by  the 
thick-walled  cells  of  the  primary  cortex  lying  at  the  periph- 
ery, and  by  a  sheath  of  somewhat  similar  cells  around 
each  bundle.  The  vascular  bundles  consist  of  the  same 
parts  as  those  of  Aristolochia,  the  xylem  facing  the  center 
and  the  phloem  the  circumference.  There  is,  however, 
no  cambium  between  the  two  parts  of  the  bundle,  and  the 
latter  does  not  therefore  increase  indefinitely  in  size,  but 
soon  attains  to  its  maximum  dimensions.  In  corn,  the 


FIG.  20. 

Cross  section  of  a  stem  of  Indian  corn, 
a, epidermis;  b, primary  cortex;  c, peri- 
cycle;  d.  vascular  bundle;  e,  ground 
tissue. 


Buds  and  Stems.  53 

general  ground  tissue  in  which  the  bundles  are  embedded 
serves  the  functions  of  the  pith,  medullary  rays,  and  thin- 
walled  portion  of  the  pericycle  and  primary  cortex,  as 
stated  for  Aristolochia. 

68.  Make  an  outline  drawing  of  the  parts  of  the  cross 
section  of  the  stem  of  corn  and  use  the  colors  to  designate 
the  same  functions  which  they  were  made  to  represent  for 
Aristolochia.      Thus  the  epidermis  would  be  blue  as  be- 
fore, the  thin-walled   cells   of   the   primary  cortex  green, 
while  its  thick-walled  cells  would  be  red ;  the  thin-walled 
tissues  in  which   the   bundles   are  embedded  yellow,  the 
phloem  purple,  the  xylem  orange,  and  the  narrow  zone  of 
thick-walled  tissue  bordering  the  bundles  red.     The  colors 
will  assist  in  comparing  the   different   parts  of  the  stem 
from  the  standpoint  of  their  use,  blue  meaning  that  pro- 
tection is  given ;  green,  that  food  is  manufactured,  tempo- 
rarily stored,  and  slowly  conducted  away  as  needed ;  red, 
that  strength  is  imparted ;  yellow,  that  food  is  stored  and 
slowly  conducted ;  purple,  that  food  materials,  and  partic- 
ularly proteids,  are  rapidly  carried  either  up  or  down  the 
stem  where  need  is  urgent;  orange,  that  water  is  rapidly 
carried   from    roots   to  leaves ;    uncolored,  that   the  cells 
are  rapidly  multiplying   and   increasing   the   diameter   of 
the  stem. 

69.  Plant  seeds  of  garden  balsam  in  moist  sawdust,  and 
keep  watered  with  well  water.     As  soon  as  the  seedlings 
appear  place  one  lot  near  a  window,  and  another  lot  on  a 
side  of  the  room  remote  from  the  windows  where  the  light 
is  not  intense.     Note  the  difference  in  rate  of  growth,  in 
the  relative  lengths  of  the  internodes,  and  in  the  size  of 
the  leaves.     Do  the  stems  grow  upright ;  if  not,  what  force 
is   interfering   with    gravity?     Carefully  remove    some  of 
both  lots  of  seedlings  from  the  sawdust   and   place  in  a 


54  Introduction  to   Botany. 

tumbler  or  wide-mouth  bottle  containing  a  weak  solution  of 
fuchsin,  and  keep  the  roots  covered  with  this  solution  until 
a  red  color  appears  in  the  veins  of  the  leaves.  The  stain 
will  color  the  tissues  through  which  it  passes  and  thus 
mark  out  the  paths  of  the  ascent  of  water.  Balsam  stems 
are  sufficiently  transparent  to  allow  the  tissues  near  the 
center  to  be  seen  from  the  outside. 

70.  Remove  a  ring  of  bark  about  an   inch  long  from 
some  twig  or  sapling  which  is  in  leaf  (the  willow  serves 
excellently  for  this  and  the  following  experiment  because 
its  bark  is  strong  and  easily  separates  from  the  wood),  and 
note  whether  the  leaves  wither.     Watch  the  experiment 
for  several  days.     Operate  on  another  twig  or  sapling  in 
the    following    manner :     Make    a    longitudinal    incision 
through  the  bark  an  inch  or  more  long,  depending  on  the 
diameter  of  the  stem,  and  then,  with  a  thin,  smooth  stick 
work  the  bark  loose  around  the  stem,  inserting  the  stick 
through  the  longitudinal  slit.     Cut  the  wood  of  the  stem 
nearly  in  two,  and  then  bend  the  stem  until  it  breaks, 
the  broken  ends  protruding  through  the  slit  in  the  bark. 
Trim  off  the  ends  so  that  they  will  not  touch  each  other ; 
then  hold  the  stem  upright  so  that  the  ends  are  again  cov- 
ered by  the  bark,  and  bind  splints  around  the  outside  to 
keep  them  in  place.     Care  should  be  taken  during  this 
operation  that  the  bark  is  not  injured  except  by  the  longi- 
tudinal slit.     Note  the  effect  on  the  leaves  in  the  course  of 
a  few  hours.     What  do  these  experiments  teach  as  to  the 
region  of  water  ascent  in  plants  ? 

71.  Remove  a  ring  of  bark  from  a  branch  or  sapling 
that  can  be  conveniently  watched,  and  note  the  result  at 
the  end  of  the  season's  growth.    What  do  the  results  teach 
as  to  the  region  of  transfer  of  food  materials  necessary  to 
the  building  up  of  new  tissues  ? 


Buds  and  Stems.  55 

72.  Make  thin  cross  sections  of  stems  of  elm,  cotton- 
wood,  or  other  woody  plants  which  were  placed  in  alcohol 
in  late  summer,  and  treat  with  iodine.  Can  reserve  food 
in  the  form  of  starch  or  proteids  be  made  out?  (The 
starch  would  be  colored  blue  by  the  iodine,  and  the  pro- 
teids from  yellow  to  brown.)  Compare  with  these  sec- 
tions others  of  stems  of  the  same  plants  taken  at  the  time 
of  unfolding  of  the  buds  in  the  spring.  What  changes 
have  taken  place  in  the  reserve  materials  ? 

DISCUSSION. 

37.  Upward  Growth  of  the  Shoot. — We  have  noticed  that 
in  the  germination  of  seeds  the  shoot  grows  straight  upward 
into  the  sunlight  and  air  just  as  uniformly  and  persistently 
as  the  roots  grow  downward  into  the  soil,  and  it  might  be 
inferred  from  this  alone  that  the  upward  growth  of  the 
shoot  is  just  as  necessary  to  the  well-being  of  the  plant  as 
the  downward  growth  of  the  root.  It  has  been  noticed 
that  as  the  shoot  reaches  the  surface,  either  the  cotyledons 
spread  out  in  the  form  of  thin  green  leaves,  or  the  first 
leaves  of  the  plumule  bud  quickly  unfold  and  place  their 
broad  surfaces  more  or  less  at  right  angles  to  the  light 
from  the  sky,  as  in  the  case  of  the  Lima  bean,  whose 
cotyledons  are  so  gorged  with  food  materials  that  they 
are  prevented  from  developing  into  useful  foliage  leaf 
forms.  As  the  stem  continues  in  its  elongation,  it  puts 
forth  new  leaves  until  it  is  nearly  concealed  by  them  and 
is  apparently  subordinate  to  them.  It  may,  in  fact,  be 
stated  that  the  chief  function  of  stems  is  to  bear  leaves, 
in  such  positions  and  at  such  distances  apart  as  to  give 
them  free  access  to  the  sunlight  and  air,  and  to  keep  them 
in  communication  with  the  water  and  other  raw  food  ma- 
terials which  are  absorbed  by  the  roots. 


56  Introduction   to   Botany. 

38.  Protection  against  Drying. — As  soon  as  the  shoot 
appears  above  the  ground  it  is  in  danger  of  drying  up,  or 
of  becoming  bruised  or  broken.     To  guard  against  drying, 
the  outer  wall  of  the  epidermis  or  exterior  layer  of  cells 
becomes  infiltrated  with  a  compound  of  fatty  and  waxy 
substances  known  as  cutin,  and  so  is  rendered  almost  im- 
pervious to  water.     Every  one  has  noticed  how  quickly  an 
apple  shrinks  and  drys  when  its  epidermis  has  been  removed 
by  paring,  and  it  would  be  a  simple  matter  to  demonstrate 
that  any  young  or  succulent  stem  would  quickly  become 
dry  if  its  epidermis  were  stripped  off. 

39.  How  Stems  are  Strengthened.  —  In  order  to  strengthen 
the  stem,  the  walls  of  the  cells  in  certain  regions  become 
thickened,  and  sometimes  woody,  and  the  cells  often  be- 
come elongated  and  more  or  less  interlaced,  as  in  the  case 
of  wood  and  bast  fibers.     As  evidence  of  the  effectiveness 
of  wood  and  bast  in  strengthening  stems,  let  the  great  elas- 
ticity and  strength  of  some  of  the  well-known  woods,  such 
as  hickory,  be  called  to  mind,  and  the  fact  that  hemp  rope 
and  linen  thread  are  made  from  the  bast  of  plants. 

The  stress  which  the  strengthening  elements  must  over- 
come is  produced  usually  by  the  wind  and  the  weight  of 
the  crown  of  the  plant.  The  force  of  the  wind  bends  the 
stem,  producing  a  stretching  of  the  elements  on  one 
side  and  a  compression  on  the  other,  while  the  weight  of 
the  crown  produces  a  compressing  effect  simply.  It  is 
clear  that  if  a  given  amount  of  strengthening  material  be 
distributed  in  the  form  of  a  hollow  cylinder,  all  stresses  of 
the  above  nature  can  be  overcome  to  the  best  advantage. 
We  find,  accordingly,  the  strengthening  elements  of  the 
pericycle  of  Aristolochia  arranged  in  this  form,  and  the 
same  is  true  of  the  strengthening  elements  in  the  primary 
cortex  of  corn,  and  of  the  wood  and  bast  fibers  in  the 


Buds  and  Stems.  57 

stems  of  plants  in  general  ;  but  in  the  roots,  where  the 
stress  is  applied  more  nearly  as  a  straight  pull,  we  find  the 
strengthening  elements  in  the  form  of  a  compact  column 
at  the  center,  a  form  which  is  best  adapted  to  resist  a 
longitudinal  pulling  stress.  In  the  distribution  of  their 
strengthening  elements,  plants  have  been  obliged  to  take 
account  of  many  things,  such  as  economy  of  materials, 
the  free  circulation  of  materials,  and  the  formation  of 
branches. 

40.  Conduction  of  Materials.  —  The  conducting  elements 
of  the  stem  are  quite  as  important  as  the  strengthening 
elements.  The  leaves  give  off  large  amounts  of  water  by 
transpiration,  and  must,  therefore,  constantly  receive  com- 
pensating supplies  from  the  roots.  "To  facilitate  the  pas- 
sage of  water,  long  tubes  are  provided,  extending  from  the 
roots  into  the  leaves.  These  tubes,  known  as  tracheal 
tubes,  have  relatively  large  openings,  and  their  walls  are 
thickened  in  various  ways  (see  Fig.  21)  so  as  to  strengthen 
them,  and  at  the  same  time  leave  thin  places  for  the  pas- 
sage of  water  into  the  tissues  along  their  route,  and  to 
allow  the  passage  of  food  materials  into  the  tubes  while 
they  are  yet  in  state  of  formation.  The  thin  places  in  the 
tubes  also  serve  another  purpose  every  spring,  in  permit- 
ting the  reserve  food  materials  in  the  underground  parts 
and  lower  regions  of  the  stems  to  pass  into  the  tubes  and 
be  carried  rapidly  upward  to  the  unfolding  buds  by  the 
ascending  currents  of  water.  The  tracheal  tubes  have 
cross  partition  walls  in  them  which  are  about  eighteen 
inches  to  three  feet  apart  ;  these  are  thin,  however,  and 
do  not  much  retard  the  passage  of  the  water. 

The  tracheal  tubes  lie  in  the  xylem  portion  of  the  vas- 
cular bundles  and  are  thus  within  the  cambium  ring. 
Accordingly  when  the  bark  is  removed  from  a  stem,  the 


58  Introduction  to   Botany. 

tracheal  tubes  are  left  intact,  since  the  bark  separates  at 
the  cambium  ring  (see  Fig.  21).  This  accounts  for  the  fact 
that  the  leaves  do  not  wither  when  the  bark  is  removed  by 
girdling. 

While    water   is   being  supplied  through  the  roots  the 
most  important  process  of  the  manufacture  of  food  mate- 


Diagrammatic  representation  of  the  structure  of  a  Stem, 
the  bark  being  partly  stripped  off  at  the  cambium  ring. 
z  o  and  p,  tracheal  tubes,  which  carry  the  water  upward 

from  the  roots ;  thin  places  are  seen  in  the  walls  of  these  tubes  in  the  form  of 
pits  and  rings,  w  and  x,  sieve  tubes  which  carry  food  down  from  the  leaves,  or 
up,  as  needed,  v,  medullary  ray,  which  carries  water  and  food  radially  to  and 
from  the  bark  and  the  wood  as  needed,  z,  bast  fibers.  Cells  of  the  cambium 
ring  are  clearly  shown  to  the  right  of  the  sieve  tube,  x. 


rials  is  taking  place  in  the  leaves,  and  highways  must  be 
provided  for  the  transport  of  these  food  materials  down- 
ward and  upward  wherever  growth  in  length  or  in  thick- 
ness is  taking  place.  The  tracheal  tubes  could  not  answer 
this  purpose  because  the  upward  movement  of  the  water 
through  them  would  prevent  the  passage  of  food  materials 


Buds  and  Stems.  59 

downward.  The  sieve  tubes  in  the  phloem  portion  of  the 
bundle  outside  the  cambium  ring  (see  Fig.  21)  seem  to  be 
.the  highways  for  these  food  materials.  The  sieve  tubes 
are 'thin-walled  and  allow  the  food  materials  to  pass  to  and 
from  the  surrounding  tissues  as  needed.  They  have  cross 
partitions  at  frequent  intervals  to  strengthen  them,  but  the 
partitions  are  perforated  so  that  materials  may  pass  rapidly 
through  them. 

41.  Effect  of  Girdling.  — When  a  tree  is  girdled,  the  sieve 
tubes  are  removed  with  the  bark  (see  Fig.  21),  and  the  parts 
of  the  stem  and  of  the  roots  below  the  girdle  are  no  longer 
supplied  with  food.  While  the  portions  of  the  stem  above 
the  girdle  increase  in  thickness  and  length  as  usual,  all 
parts  of  the  plant  below  the  girdle  are  restricted  in  growth 
because  the  main  food  supply  is  shut  off.  If  the  bark  of 
a  stem  is  removed  early  in  the  spring,  before  the  leaves  are 
out,  the  usual  process  of  the  unfolding  of  leaf  and  flower 
buds  may  still  take  place  because  the  reserve  materials 
stored  in  the  underground  parts  and  in  the  lower  portion  of 
the  trunk  may  be  carried  upward  by  the  water  currents  in 
the  tracheal  tubes ;  but  the  following  year,  if  the  bark  has 
been  completely  removed  in  the  girdle,  and  no  twigs,  bear- 
ing leaves  have  been  allowed  to  grow  below  the  girdle,  the 
roots  will  not  have  stored  in  them  the  food  necessary  to 
the  production  of  new  rootlets  and  root  hairs,  and  thus 
can  no  longer  absorb  the  water  necessary  to  the  resump- 
tion of  growth.  The  advantage  of  girdling  trees  which 
are  to  be  cut,  down  lies  in  the  fact  that  the  stump  and 
roots  below  tHe  girdle  will  thereby  be  prevented  from  re- 
ceiving the  food  which  might  be  employed  in  the  produc- 
tion of  new  shoots  from  adventitious  buds  on  the  stump  or 
roots.  In  stems  of  the  type  of  Indian  corn  and  palm  there 
can  be  no  separation  of  the  food-conducting  and  the  water- 


6o 


Introduction  to  Botany. 


conducting  elements  by  the  process  of  girdling,  for  the 
reason  that  the  bundles  are  scattered  promiscuously 
throughout  the  stem  (Fig.  20). 

42.  Summary  of  Structure  and  Function.  —  When  we  re- 
view the  details  in  the  plan  of  construction  of  typical  stems, 
we  see  that  they  are  so  admirably  adapted  to  give  strength 

and  facilitate  transport  that 
trees  can  withstand  the  storms 
of  centuries,  and  the  inter- 
change of  materials  between 
roots  and  leaves  can  continue 
without  interruption  even  in 
trees  which  have  reached  a 
height  of  four  hundred  feet. 
We  see  that  the  strengthening 
elements  are  laid  down  ac- 
cording to  approved  mechan- 
ical principles,  and  that  the 
conducting  system  is  a  double 

Diagram  showing  medullary  rays  from        .  J 

cross,  tangential,  and  radial  points  of     highway    along    which     mate- 


n     °PP°site 

directions  without   hindering 

each  other  in  the  least  degree.  We  find  that  the  movement 
of  materials  radially  is  provided  for  by  the  medullary  rays, 
which  extend  individually  only  a  short  distance  longitu- 
dinally, and  so  are  prevented  from  transporting  materials  in 
any  other  than  the  radial  direction  (see  Fig.  22). 

43.  Transporting  Forces.  —  The  forces  which  are  con- 
cerned in  carrying  the  water  upward  have  not  yet  been 
demonstrated  with  certainty.  Atmospheric  pressure  does 
not  suffice  to  carry  water  to  the  height  of  tall  trees  ;  capil- 
larity in  the  tracheal  tubes  cannot  lift  the  water  beyond 
the  height  of  a  middle-sized  tree  ;  and  osmotic  pressure  in 


Buds  and  Stems.  61 

the  roots  cannot  provide  water  fast  enough  to  supply  the 
loss  by  transpiration.  Neither  does  the  lifting  power 
appear  to  be  due  to  living  cells  in  the  roots  or  stem  acting 
after  the  manner  of  a  heart,  or  in  any  other  way ;  for  after 
these  cells  have  been  killed  by  poisonous  solutions  the 
water  continues  to  rise  and  evaporate  from  the  leaves.  It 
seems  probable  that  the  leaves  themselves  assist  in  lifting 
the  water,  perhaps  by  osmotic  action  between  the  tracheal 
tubes  and  the  parenchyma  cells  in  the  leaves;  but  this 
has  not  been  satisfactorily  demonstrated.  The  problem  of 
the  ascent  of  water,  although  apparently  simple  on  the 
face  of  it,  has  been  one  of  the  most  elusive  in  plant  physi- 
ology. The  forces  concerned  in  the  rapid  movement  of 
food  materials  through  the  sieve  tubes  also  remain  undem- 
onstrated.  Diffusion  would  account  for  slow  movements, 
but  the  sieve  tubes  are  evidently  designed  for  conducting 
more  rapid  hydrostatic  currents.  ^ 

44.  Direction  of  Growth.  —  We  have  seen  that  the  shoot 
of  the  young  seedling  employs  gravity  to  direct  its  course 
upward.     After  it  appears  above  the  ground,  however,  it 
does  not  necessarily  continue  in  a  vertical  direction,  but 
may  grow  more  or  less  nearly  horizontal,  and  may  even 
turn   downward.     If   the   stem    becomes   more    intensely 
illuminated    on   one   side   than    another,  it  usually  grows 
toward  the  region  of  greatest  illumination,  but  in   some 
climbing  plants  it  may  grow  in  the  opposite  direction  and 
thus  keep  in  close  contact  with  its  support. 

45.  Gravity  as  Guide.  — While  the  plant  employs  grav- 
ity as  a  guide  in  bringing  the  shoot  out  of  the  ground,  it 
also  uses  the  same  force  in  conjunction  with  light  to  guide 
it  in  placing  its  branches  at  various  angles  to  the  vertical, 
as  its  needs  may  require.     Although  it  may  be  stated  as  a 
rule  that  shoots  which  are  formed  beneath  the  surface  of 


62 


Introduction  to  Botany. 


the  soil  are  directed  upward  by  gravity,  this  is  by  no  means 
always  the  case.     Certain  underground  shoots  of  the  po- 
tato, for  instance,  are  directed 
downward    at    various    angles, 
and  the  underground  shoots  of 
the  goldenrod  are  guided  in  a 
horizontal  direction.     In  Sagit- 
taria  variabilis  we  find  an  in- 
teresting example  of 
somewhat   diverse 
habits.     Radiating  in 
various  directions 
from  the  parent  plant 
(m,  Fig.  23)  are  hor- 
izontal  underground 
shoots     (g)t     which 
finally   turn   upward 
at  the  apices  (//)  and 
produce     leaves 
above    the    surface. 
Roots  are  produced 
at  the  basal  node  of 
the    upright    shoots, 
which   then    become 
independent    indi- 
viduals (z).     Later  in 
the     season,     under- 
ground    shoots    (/) 
are   produced   which 
grow    vertically 
downward  for  about 

a  foot,  and  then  turn  upward  at  their  apices  for  a  short 
distance    and    form    bulbs    (e)    that    become    filled  .with 


Sagittaria  variabilis.  d,  last  year's  tuber,  from 
which  the  central  plant  (m)  has  sprung;  g,  off- 
shoots from  m\  h,  terminal  bud  of  g,  which  has 
turned  upward  and  will  produce  a  plant  like  i ; 
f,  offshoot  which  has  grown  down  into  the  mud 
and  will  produce  a  tuber  similar  to  e,  which  is  a 
tuber  of  the  current  season  destined  to  survive  the 
winter  and  then  produce  a  new  plant,  as  d  has 
done. 


Buds  and  Stems.  63 

reserve  food  materials,  and  in  this  position  survive  the 
winter. 

In  the  spring  the  terminal  shoot  produced  from  a  bulb 
grows  vertically  upward  (d)  and  sends  forth  leaves  and 
flowers ;  while  at  a  node  a  short  distance  below  the  sur- 
face of  the  mud,  roots  are  formed,  and  also  buds,  from 
which  the  horizontal  shoots  arise,  thus  bringing  us  back  to 
the  stage  at  which  we  began  the  cycle.  This  example  is 
an  exceedingly  instructive  one  in  showing  how  plants  may 
employ  any  force  acting  in  a  definite  direction  (in  this  case 
gravity),  not  in  impelling  all  of  its  parts  in  one  direction, 
but  as  a  fixed  line  from  which  may  be  determined  the 
various  directions  toward  which  its  different  members 
should  grow.  It  is  also  instructive  in  another  way :  it 
shows  that  plants  are  not  inert  bodies,  but  are  possessed 
of  a  high  degree  of  sensibility  which  enables  them,  in  a 
certain  sense,  to  perceive  their  condition  and  the  forces 
within  whose  range  they  are  lying.  Notice,  for  instance, 
that  the  horizontal  shoots  of  Sagittaria  do  not  grow  indefi- 
nitely in  the  horizontal  direction,  but  after  a  suitable  dis- 
tance from  the  parent  plant  has  been  traversed  so  that 
danger  of  crowding  is  avoided,  they  turn  upward  and  pro- 
duce leaves  and  roots.  So,  too,  the  downward-growing 
shoot,  having  reached  a  depth  where  the  winter  may  be 
passed  in  safety,  turns  upward  and  produces  the  bulb  to 
which  is  intrusted,  as  well  as  to  the  seeds,  the  life  of  suc- 
ceeding generations. 

46.  Light  as  Guide.  — Where  gravity  cannot  be  employed 
as  a  guide  in  achieving  certain  results,  light  may  be  used 
instead.  If  the  stem  has  a  climbing  habit  and  is  supported 
by  lateral  outgrowths  in  the  form  of  suckers  or  roots  which 
are  able  to  obtain  foothold  on  walls,  trees,  etc.,  the  shoot 
employs  the  line  of  propagation  of  the  greatest  incident 


FIG.  24. 

Mature  plant  and  two  seedlings  of  the  Trumpet  Creeper.  The  seedlings  are 
growing  toward  the  wall  and  away  from  the  source  of  greatest  illumination. 
On  the  mature  plant  the  flowering  branches  are  growing  away  from  the 
wall  and  toward  the  source  of  greatest  illumination. 


Buds  and  Stems.  65 

light  to  guide  it  toward  its  support.  The  common  trumpet 
creeper,  Tecoma  radicans,  acts  in  this  way.  Figure  24  is 
a  drawing  from  nature  showing  seedlings  which  have 
started  at  some  distance  from  the  wall  toward  which  they 
have  sharply  turned ;  their  leaves,  however,  are  facing  the 
light.  As  this  plant  climbs  a  wall  its  shoots  lie  close 
against  it,  so  that  the  clinging  roots  easily  get  a  foothold. 
But  the  shoots  that  are  to  produce  flowers  as  well  as  leaves 


FIG.  25. 
Ltnaria  cymballaria  clambering  over  rocks.    After  KERNER. 

turn  toward  the  light  instead  of  from  it  (see  Fig.  24),  so 
that  the  flowers  may  be  easily  detected  by  the  insects  and 
humming  birds  which  assist  in  their  cross  pollination  (see 
page  170).  A  no  less  marvelous  example  in  which  the 
sensibility  of  the  plant  involves  a  perception  of  its  own 
condition  (conscious  recognition  is  of  course  not  meant)  is 
furnished  by  the  behavior  of  the  flower  stems  of  Linaria 
cymballaria,  a  clambering  plant  which  fastens  itself  to 
walls,  etc.,  by  means  of  suckers.  The  pedicels  bearing 
newly  opened  flowers  turn  outward  toward  the  source  of 
greatest  light  so  that  the  flowers  are  noticeable  to  those 


66 


Introduction  to   Botany. 


insects  which  are  necessary  to  their  cross  pollination ;  but 
after  fertilization  has  been  achieved  and  the  production  of 
seeds  thereby  insured,  the  pedicels  turn  from  the  light  and 
deposit  the  seed  pods  in  the  crannies  of  the  rocks,  where  they 
may  find  a  suitable  place  for  their  germination  (Fig.  25). 

47.  Formation  of  Leaves. — We  have  noticed,  in  follow- 
ing the  development  of  seedlings,  that  leaves  are  produced 
at   definite   intervals   along  the  stem  as  the  shoot   elon- 
gates.   The  segments  of  the 
stem  which  bear  the  leaves 
are  called  the  nodes,  while 
the,  portions  of  the  stem  be- 
tween the  nodes  are  termed 
the  internodes.     An  exami- 
nation of  the  apical  bud  of 
the  shoot,  with  the  simple 
lens,  reveals  the   fact   that 
the  leaves  are  begun  as  lat- 
eral outgrowths  of  the  stem 
quite   close  to  the  growing 
point,  the  apical  bud  consist- 
ing, in  fact,  of  a  succession 

Honey  locust  with  deliquescent  trunk.        of     immature,    nodes,     inter- 

nodes,  and  leaves. 

48.  Summer  and  Winter   Buds.  —  In    some   plants,  the 
growing  point  of  the  shoot  continues  to  give  rise  to  new 
nodes,  internodes,  and  leaves  throughout  the  growing  sea- 
son, so  that  when  winter  sets  in  there  is  a  certain  unripe 
portion  of  the  shoot  extending  back  from  the  apex  which 
is  killed  by  the  cold,  or  its  buds  are  weak,  and  the  continu- 
ation of  growth  the  following  season  devolves  on  buds  on 
older  portions  of  the  stem.     In  such  plants  the  crown  is 
much  branched  and  has  no  main  central  trunk  (see  Fig.  26). 


FIG.  26. 


Buds  and  Stems. 


67 


In  other  plants,  such  as  the  horse-chestnut,  hickory,  and 
cottonwood,  the  elongation  of  the  stem  ceases  before  the 
close  of  the  growing  season.  In  such  cases  a  few  of  the 
last-formed  internodes  fail  to  elongate,  while  the  leaves  of 
some  of  the  lower  nodes  subtending  the  short  internodes 
grow  up  in  the  form  of  scales,  completely  enwrapping  all 
of  the  parts  above  them,  and  protecting  them  against 
mechanical  injury  and  the 
vicissitudes  of  weather. 
Such  buds  are  quite  certain 
to  survive  the  winter,  and, 
if  stronger  than  the  lateral 
buds,  to  continue  the  growth 
of  the  shoot  the  following 
spring,  so  that  the  main 
shoot  of  such  plants  is  apt 
to  retain  its  identity  in  the 
form  of  a  central  shaft  ex- 
tending through  the  crown 
(see  Fig.  27).  Buds  which 
ripen  and  prepare  for  winter 
are  termed  winter  buds ; 
while  the  buds  which  do 
not  ripen,  and  die  or  re- 
main weak  in  consequence,  may  be  called  summer  buds. 
49.  Protection  afforded  Winter  Buds.  —  The  study  of  the 
winter  buds  of  the  horse-chestnut  and  cottonwood  has 
shown  that  the  leaves  formed  at  the  uppermost  nodes  are 
ordinary  foliage  leaves  in  an  embryonic  state,  and  conse- 
quently in  need  of  protection.  The  amount  and  character 
of  protection  afforded  to  the  tender  parts  of  winter  buds  is 
quite  different  for  different  plants.  As  has  already  been 
observed  by  the  student,  the  outer  scales  of  the  buds  of 


FIG.  27. 
Oak  with  excurrent  trunk. 


68  Introduction  to  Botany. 

horse-chestnut  'and  of  hickory  are  hard  and  dry  and  well 
adapted  to  give  protection  against  mechanical  injury, 
while  the  hairs  growing  over  the  scales  tend  to  keep  them 
separated  slightly,  and  so  form  dead  air  spaces  which  retard 
the  escape  of  water  from  the  succulent  parts  of  the  bud, 
and,  on  account  of  the  slight  conductivity  of  air  for  heat, 
protect  the  inner  parts  against  sudden  changes  in  tempera- 
ture. In  the  winter  buds  of  the  cottonwood,  the  tender 
parts  are  prevented  from  drying  up  by  resinous  substances 
which  hold  the  scales  closely  together.  The  amount  of 
protection  required  by  buds  varies  greatly  for  different 
plants,  and  depends  largely  upon  the  ability  of  their  pro- 
toplasts to  withstand  adverse  conditions.  The  buds  of 
some  plants  are  able  to  pass  through  severe  winters  in 
safety  without  any  special  means  of  protection.  Even  in 
the  arctic  regions  there  are  plants  whose  buds  are  able  to 
survive  the  intense  cold  while  in  a  succulent,  half -formed 
condition.  The  degree  of  protection  given  to  buds  seems, 
therefore,  to  be  regulated  by  the  needs  of  the  living  cells. 

50.  Disposition   of  Leaves   in   Buds.  —  The   manner   in 
which  the  embryonic  foliage  leaves  are  packed  away  in  the 
bud  is  not  the  same  in  all  cases ;  but,  however  these  details 
may  vary,  the  leaves  already  possess  in  the  bud  the  regular 
angular  divergence  on  the  stem  which  is  found  in  mature 
shoots,  and  this  facilitates  their  disposition  in  the  very  small 
compass  of  the  bud. 

51.  Unfolding    of    Winter    Buds. — The    unfolding    of 
winter  buds  in  the  spring  is  essentially  the  resumption  of 
growth  in  parts  already  formed.    The  short  internodes  and 
the  minute  leaves  quickly  elongate  and  expand,  and  almost 
in  a  day  the  trees  are  again  covered  with  foliage.     Such 
remarkable  development  would  be  impossible   if   reserve 
food  materials  were  not  already  at  'hand  for  the  building 


Buds  and  Stems.     .  69 

up  of  new  tissues.  The  reserve  materials  can  be  demon- 
strated by  using  tests  for  starch,  proteids,  sugar,  oils,  etc., 
chiefly  in  the  medullary  rays  and  wood  parenchyma  cells 
of  the  stems  and  underground  parts.  Before  these  mate- 
rials are  needed  in  the  spring,  those  which  are  insoluble  or 
poorly  diffusible  are  changed  by  appropriate  ferments  so 
that  they  can  pass  by  diffusion  from  cell  to  cell,  or  be  carried 
more  rapidly  upward  by  the  ascending  currents  of  water. 
Buds  which  remain  attached  to  the  parent  plant  and  are 
able  to  draw  upon  it  for  their  food  do  not  need  to  have  the 
reserve  materials  stored  within  their  own  tissues,  as  in  the 
case  of  seeds  which  are  cast  off  from  the  parent  and  left 
thereafter  to  shift  for  themselves. 

52.  Leaf  and  Flower  Buds.  —  Dissection  of  the  terminal 
buds  of  the  horse-chestnut  reveals  the  fact  that  many  of  them 
contain  flowers  as  well  as  leaves,  while  the  terminal  buds 
of  the  lilac  may  contain  only  flowers.  In  the  cottonwood 
we  find  many  of  the  lateral  buds  containing  flowers  only, 
while  the  terminal  buds  contain  only  leaves.  When  we 
inquire  the  reason  why  the  growing  point  of  certain  form- 
ing buds  gives  rise  to  leaves  and  that  of  others  to  flowers, 
or  to  both  leaves  and  flowers,  we  are  unable  to  obtain  a 
satisfactory  answer.  We  know,  however,  that  some  peren- 
nial plants  produce  only  leaf  buds  for  a  number  of  years, 
and  are  not  able  to  form  flowers  until  they  have  attained  a 
certain  age ;  we  do  not  expect  apple  trees,  for  instance,  to 
bear  flowers  until  they  are  five  years  old  or  more.  The 
century  plant  does  not  produce  flowers  until  it  has  attained 
an  age  of  twenty  to  thirty  years.  We  know,  too,  that 
shoots  which  would  otherwise  terminate  with  winter  budk 
containing  leaves  only  can  be  made  to  terminate  with  buds 
containing  flowers  if  the  branch  on  which  the  shoot  is 
borne  is  pruned  back,  or  if  the  roots  are  pruned.  By  this 


jo  Introduction  to  Botany. 

means  the  fruit  grower  is  able  to  increase  very  materially 
the  yield  of  his  trees.  It  seems  from  observations  on  dif- 
ferent forms  throughout  the  plant  kingdom  that  under 
conditions  of  good  nutrition,  if  changes  occur  which  check 
mere  vegetative  growth,  and  are  not  inimical  to  the  life  of 
the  plant,  then  the  activity  of  the  plant  is  apt  to  manifest 
itself  in  the  formation  of  reproductive  organs.  The  results 
of  pruning  back  branches  and  roots  illustrate  this  for  the 
higher  plants. 

53.  Position  of  Buds.  —  Buds  usually  occur  at  the  apices 
of  branches  and  laterally  in  the  axils  of  the  leaves ;  in  the 
latter  position  they  are  termed  axillayy,  and  in  the  former, 
terminal.     Buds  which  sometimes  occur  beside  or  above 
the  axillary  buds  are  called  accessory.     Sometimes,    how- 
ever, buds  occur  without  order  on  both  stems  and  roots, 
and  are  then  called  adventitious.     Both  axillary  and  acces- 
sory buds  have  the  same  angular  divergence  as  the  leaves, 
and  their  growth  under  good  conditions  results  in  a  sym- 
metrically shaped  plant.     Always  many  buds  are  formed 
which  never  develop  into  shoots ;  or  some,  after  lying  dor- 
mant for  years,  may  resume  their  growth  if  accidents  to  the 
plant  require  the  production  of  new  shoots  on  the   old 
branches.     Adventitious  buds  occur  normally  on  the  roots 
of  certain  plants,  such  as  the  white  poplar,  but  they  usually 
appear  only  as  the  result  of  injuries  —  as  illustrated  by  the 
numerous  shoots  which  grow  forth  on  the  stumps  of  felled 
trees. 

54.  The  Nature  of  a  Bud.  —  Whether  a  bud  gives  rise  to 
leaves  or  flowers,  or  to  both  leaves  and  flowers,  it  is  essen- 
tially a  miniature  shoot  whose  succession  of   internodes, 
nodes,  and  lateral  outgrowths  is  but  a  repetition  of  a  simi- 
lar succession  dating  back  to  the  germination  of  the  seed, 
and  constituting  the  whole  above-ground  body  of  the  plant. 


Buds  and  Stems. 


We  might  expect,  then,  that  a  bud  would  have  all  of  the 
potentialities  possessed  by  the  entire  plant.  How  true  this 
is,  is  shown  by  the  results  of  the  process  known  as  bud- 
ding, which  is  practiced  by  nurserymen  for  the  propaga- 
tion of  various  sorts  of  plants. 

55.  Propagation  by  Budding.  —  In  this  process,  a  bud, 
together  with  the  bark  and  a  very  thin  layer  of  the  wood 
just  beneath  it,  is  re- 
moved from  the  plant 
which  it  is  desired  to 
propagate  (a,  Fig.  28). 
A  longitudinal  slit  about 
an  inch  long  is  made  in 
the  bark  of  the  plant  on 
which  the  bud  is  to  be 
grown,  and  at  the  top 
of  the  longitudinal  slit 
a  cross  slit  is  made  so 
that  the  bark  may  be 
separated  from  thewood. 


FIG.  28. 


Process  of  Budding,  a,  cutting  the  bud  from 
the  parent  branch ;  b,  inner  surface  of  the 
removed  portion,  showing  the  base  of  the 
petiole,  and  beneath  it  a  bit  of  wood  adher- 
ing to  the  base  of  the  bud ;  c,  the  bud  placed 
in  position  and  partly  tied  in.  After  BARRY. 

The  bud  is  then  slipped 

under  the  bark  and  tied  into  position  (c,  Fig.  28).  After  a 
few  weeks  the  bud  will  have  grown  to  its  foster  stem,  and 
the  string  which  binds  it  down  is  cut  away. 

This  process  is  usually  done  in  the  summer  or  early  fall, 
and  the  bud  is  not  expected  to  grow  until  the  following 
spring,  when  all  the  branches  of  the  foster  plant  are  cut 
away,  and  it  alone  is  allowed  to  develop.  The  shoot  which 
grows  from  the  bud  is  found  to  possess  the  characters  of 
the  plant  from  which  it  was  taken,  and  the  branches  which 
later  spring  from  it  have  the  same  characters.  In  short, 
all  of  the  characters  of  the  parent  plant  were  transplanted 
by  means  of  a  single  bud ;  and  so  certain  is  this  to  occur 


Introduction  to   Botany. 


FIG.  29. 


a,  the  root, 


that  the  process  of  budding  is  relied  on  for  multiplying 
desirable  varieties  of  many  fruits  and  flowers,  such  as 
peaches,  cherries,  pears,  roses,  etc. 

56.  Propagation  by  Grafting.  —  Likewise,  if  a  small  por- 
tion of  the  branch  bearing  a  bud.  be  inserted  into  the  stem 
of  another  closely  allied  plant  which  is  rooted  in  the  soil, 
after  the  manner  represented  in  Fig.  29,  the  correspond- 
ing parts  of  the  two  will  grow 
together,  and  the  branches  aris- 
ing from  the  bud  of  the  engrafted 
stem  will  possess  essentially  the 
same  characters   and  bear   the 
same  kind  of  fruit  as  the  plant 
from  which  the  stem  was  taken. 
This  process  is  known  as  grafting, 
and  is  employed  in  the  propaga- 
tion of  various  fruits  and  flowers. 

We  learn  from  facts  of  this 
kind  that  the  powers  and  quali- 
ties of  the  plant  as  a  whole  reside  in  very  restricted  parts 
of  it ;  a  fact  of  great  importance  to  organisms  which  can- 
not seek  shelter  against  the  vicissitudes  of  weather,  but 
must  stand  in  one  place  and  meet  the  force  of  storms, 
often  with  the  result  of  mutilation  or  even  amputation  of 
their  members.  It  is  in  virtue  of  this  fact  that  all  of  the 
above-ground  parts  of  certain  plants,  such  as  Solomon's 
seal,  goldenrod,  and  Dahlia,  may  die  away  and  be  regen- 
erated on  the  return  of  spring  from  the  relatively  small 
underground  portions. 

57.  Functions  of  Stems. — While  a  typical  stem  stands 
erect  above  the  soil  and,  for  its  chief  function,  bears  leaves 
and  connects  them  with  the  roots,  yet,  in  the  economy  of 
the  plant,  stems  may  have  other  forms  and  perform  other 


Process  of  Grafting, 
and  b,  the  branch,  made  ready 
for  grafting ;  c,  grafted  root  and 
branch.  After  BARRY. 


Buds  and  Stems.  73 

services.  The  tuber  of  the  Irish  potato,  for  instance,  is  a 
portion  of  a  stem  having  for  its  chief  function  the  storage 
of  materials;  the  stems  of  cacti  are  green,  and  perform 
the  food-producing  functions;  the  underground  stems  of 
Sagittaria  and  goldenrod  creep  along  under  the  surface  of 
the  ground,  producing  new  erect  shoots  here  and  there, 
and  so  serve  the  purpose  of  multiplication ;  the  tendrils  of 
the  grape  and  Virginia  creeper,  which  seem  to  be  stems, 
have  a  supporting  function.  Indeed,  as  we  shall  learn  in 
the  chapter  on  modified  parts,  the  members  of  the  plant 
body  may  be  put  to  quite  as  various  services  as  the 
economy  of  the  plant  may  require. 

58.  Habits  of  Stems.  —  The  typical  foliage  stem  is  erect 
or  nearly  so,  and  stands  by  its  own  strength.  Climbing 
plants  do  not  possess  the  strength  nor  form  of  stem  to  en- 
able them  to  acquire  the  erect  position  without  the  aid  of 
some  support.  An  examination  of  the  structure  of  stems 
of  climbing  plants  reveals  the  fact  that  they  are  relatively 
lacking  in  the  strengthening  elements,  while  the  tubes  for 
conducting  water  occupy  a  correspondingly  larger  space. 
This  is  what  we  should  expect,  for  plants  that  have  ac- 
quired the  habit  of  clinging  to  other  objects  for  their  sup- 
port have  less  need  of  strengthening  elements,  while  their 
long  and  slender  stems,  which  lift  the  foliage  to  a  con- 
siderable height  above  the  ground,  require  that  a  relatively 
large  space  be  given  over  to  highways  for  water  transport. 
At  the  opposite  extreme  of  habit  stand  the  plants  with 
prostrate  stems,  such  as  Euphorbia  serpens.  These  two 
types  of  stems,  the  climbing  and  the  prostrate,  between 
which  all  degrees  of  gradation  may  be  found,  are  adapted 
to  quite  different  habitats,  —  the  climbing  stems  to  shady 
situations,  such  as  dark  woods,  or  the  shady  side  of  banks 
or  buildings,  and  the  prostrate  stems  to  situations  along 


74  Introduction  to  Botany. 

the  borders  of  roads,  and  rocky  and  waste  places,  where 
they  may  be  rooted  in  good  soil,  but  are  able  to  run  out 
over  the  barren  areas  where  their  leaves  will  not  be  too 
much  shaded  by  the  surrounding  vegetation. 

59.  Characterization  of  Stems.  —  When  we  survey  their 
character  and  functions,  we  find  that  stems  are  members 
of  the  plant  body  which  bear  the  leaves  and  roots,  and 
have  for  their  chief  functions  the  exposure  of  the  leaves  to 
the  light,  and  the  transport  of  materials  between  the  leaves 
and  roots.  The  other  functions  which  they  perform  seem 
to  be  adaptations  to  special  conditions. 


CHAPTER   V. 
LEAVES. 

PROVIDING  MATERIALS. 

Most  of  the  observations  on  leaves  are  best  made  in  the  field  or 
upon  materials  freshly  brought  into  the  laboratory.  If  vegetation  out 
of  doors  is  not  sufficiently  advanced  to  begin  the  study  of  leaves  as 
soon  as  the  work  on  buds  and  stems  has  been  completed,  the  study 
of  modified  structures  outlined  in  a  following  chapter  might  next  be 
taken  up,  and  the  study  of  leaves  postponed  until  the  right  kind  of 
material  can  be  obtained  in  abundance. 

OBSERVATIONS. 

In  the  study  of  leaves,  make  account  by  notes  and  draw- 
ings of  the  following  points  :  — 

73.  The  form  of  the  leaf  and  the  character  of  its  outline. 

74.  The  texture  of  the  leaf  and  the  character  of  the  two 
surfaces,  whether  rough,  smooth,  hairy,  etc. 

75.  The  manner  of  attachment  of  the  leaf  to  the  stem; 
namely,  is  it  broad  or  narrow  at  the  base  ?     Is  the  leaf 
blade  attached  to  the  stem,  or  does  a  leaf  stalk  or  petiole 
intervene  ?     Are  there  lateral  outgrowths  at  the  base  of 
the  leaf  ? 

76.  How  does  the  leaf  vary  as  it  grows  from  the  bud  ? 
Do  the  form  and  size  of  the  leaf  and  the  character  of  the 
two  surfaces  vary  materially  ?     Compare  the  color  of  leaves 
which  are  just  issuing  from  the  bud  with  that  of  mature 
leaves. 

77.  How  do  the  leaves  vary  in  form,  size,  and  outline 

75 


76  Introduction  to  Botany. 

from  the  base  to  the  summit  of  the  stem  ?     Draw  types  of 
the  different  kinds. 

78.  How  does  the  angle  made  by  the  leaf  with  the  stem 
vary  as  the  leaf  advances  from  its  embryonic  condition  in 
the  bud  to  maturity  ?     Does  the  direction  taken  by  the 
stem  seem  to  affect  this  angle  ?     To  answer  this  question 
study  the  approximately  horizontal  and  vertical  branches 
of  the  same  plant. 

79.  What  is  the  position  taken  by  the  leaves  with  refer- 
ence to  the  incident  light  ? 

Note  the  position  of  leaves  at  different  times  of  the  day 
to  find  out  whether  the  movement  of  the  area  of  greatest 
light  from  the  east  toward  the  west  affects  the  positions  of 
leaves,  and  if  so,  to  what  degree. 

80.  Determine  the  angular  divergence  of   the  leaves. 
(See  page  48.) 

8 1.  Is  there  any  relation  between  the  breadth  of  the 
leaves   and   the   number   of   vertical  rows  on  the  stem  ? 
When  the  vertical  rows  are  numerous,  are  the  leaves  more 
narrow  as  a  rule  than  when  the  rows  are  fewer  ? 

82.  Is  there  any  definite  relation  between  the  lengths  of 
the  leaves  and  their  vertical  distances  apart?     It  should 
be  remembered  that  short  leaves  will  permit  the  light  to 
strike  between  them  better  than  long  ones. 

83.  When  leaves  are  growing  close  together  in  the  form 
of  rosettes,  how  are  they  prevented  from  shading  each  other 
too  much  ?     Notice  whether  there  is  a  difference  between 
the  lower  and  upper  leaves  as  to  their  size  and  shape,  and 
their  angular  deviation  from  the  horizontal. 

84.  In  trees  and  shrubs,  do  the  leaves  on  the  horizontal 
branches  grow  from  buds  on  the  lower  as  well  as  on  the 
upper   side  ?     Do   the  leaves   seem  to  assume  a  definite 
position  with  reference  to  the  light  from  above  ? 


Leaves.  77 

85.  Is  there  any  marked  difference  in  position  and  dis- 
tribution between  leaves  on  horizontal  branches  and  those 
on  vertical  branches  ? 

86.  Make    a   longitudinal    section  with    a   sharp  knife 
through  the  middle  of  a  leaf  and  the  branch  which  bears 
it,  and  note  its  connection  with  the  bark  and  wood.     Re- 
move another  leaf  from  its  stem,  with  a  downward  pull, 
and  examine  the  wound  with  a  lens  to  see  whether  the 
broken  ends  of  the  vascular  bundles  can  be  made  out. 

87.  Make  drawings  to  show  the  course  of  the  veins  in  a 
grass  or  lily  leaf,  or  in  the  leaf  of  any  monocotyledonous 
plant;  also  drawings  of  veins  in  the  leaf  of  a  sunflower, 
castor  bean,  or  other  dicotyledonous  plant.    Bleach  any  thin 
leaf  by  soaking  it  in  strong  alcohol  until  the  chlorophyll  is 
extracted  (chlorophyll  is  the  green  coloring  matter  in  the 
leaf),  and  allowing  it  to  lie  in  a  saturated  solution  of  chloral 
hydrate  (see  page  381)  for  several  days ;  then  mount  it  in 
a  drop  of  dilute  glycerine,  and  examine  under  the  medium 
power  of   a  compound   microscope  in  order  to  note  the 
ultimate  branches  of  the  veinlets. 

88.  Cover  rapidly  growing  plants  or  branches  of  plants 
so  as  to  keep  them  dark,  and  compare  the  color  and  size 
of  the  leaves  which  develop  in  the  dark  with  that  of  leaves 
grown  under  normal  conditions  of  illumination ;  compare 
also  the  lengths  of  the  internodes  formed  in  the  two  cases. 
How  long  does  it  take  for  the  blanched  leaves  to  turn 
green  after  they  have  been  exposed  to  the  light?     Boil 
for  a  short  time  in  water  a  blanched  leaf  which  has  devel- 
oped in  this  dark  and  a  green  leaf  which  has  grown  in  the 
light,  and  place  in  alcohol  until  the  green  leaf  has  become 
colorless;  then  place  both  leaves  in  a  solution  of  iodine, 
and  note  whether  one  is  colored  more  purple  than  the 
other,  indicating  a  greater  amount  of  starch.     Sugars,  as 


78  Introduction  to  Botany. 

well  as  starch,  are  manufactured  within  the  leaf ;  but  the 
starch  is  more  readily  demonstrable,  and  will  therefore  be 
considered  here  and  in  the  discussion  as  the  visible  product 
of  the  leaf's  work. 

89.  Make  thin  cross  sections  of  a  green  leaf  and  mount 
them  in  a  drop   of  water  under  a  coverglass  and  study 
them  with  a  high  power  of  the  microscope.     Note  the 
rounded  green  bodies,  termed  chloroplasts,  lining  the  walls 
of  the  cells.     Mount  other  sections  under  a  coverglass  in 
a  drop  of  a  saturated  solution  of  chloral  hydrate  to  which 
has  been  added  sufficient  iodine  to  give  it  a  pale  brown 
color.     By  this   process   the    leaf   will   be   bleached   and 
rendered  transparent,  while  the  starch  grains  in  the  leaf 
will  be  stained  purple.     Watch  the  action  of  this  reagent 
from  the  beginning,  and  note  how  the  chloroplasts  are 
gradually  bleached,  while  the  starch  grains  in  them  become 
more  and  more  distinct.     Treat  in  this  way  sections  from 
a  leaf  taken  just  before  sunset,  and  from  another  leaf  from 
the  same  plant  taken  just  before  sunrise  the  next  morning. 
Note  the  relative  amounts  of  starch  in  the  two  sections. 
What  conclusions  do  you  reach  from  the  results  of  your 
observations  ? 

90.  Tie  a  branch  of  a  floating  water  plant,  such  as  Cera- 
tophyllum  or  Myriophyllum,  to  a  glass  rod  or  tube  and  set 
in  a  beaker  of  water,  the  glass  rod  being  about  an  inch 
shorter  than  the  depth  of  the  water.     Invert  a  test  tube 
of  water  over  the  rod  and  plant,  the  cut  end  of  the  plant 
being  uppermost  and  extending  into  the  test  tube.    Prepare 
two  other  branches  in  the  same  manner,  filling  the  second 
tube  with  water  which  has  just  been  boiled  and  cooled, 
and  the  third  with  water  which  has  been  charged  with  carbon 
dioxide  by  blowing  into  it  for  some  time  through  a  glass 
tube ;   invert  each  tube  in  a  beaker  containing  the  same 


Leaves. 


79 


kind  of  water  that  the  tube  holds.  Expose  all  three  prepa- 
rations to  the  full  light  of  the  sun.  Compare  the  results 
with  those  obtained  from  a  single  plant  placed  successively 
under  the  three  sets  of  conditions. 

The  first  tube  and  beaker  will  contain  a  moderate 
amount  of  carbon  dioxide,  the  second  little  or  none,  and 
the  third  a  great  deal.  Watch  for  bubbles  of  gas  issuing 
from  the  cut  ends  of  the  branches.  Count  the  number 
rising  from  each  in  a  given  unit  of 
time.  The  green  leaves  are  taking 
carbon  dioxide  from  the  water  and 
are  dissociating  the  carbon  and  oxy- 
gen, retaining  the  carbon  for  the 
manufacture  of  starch,  and  liberat- 
ing part  of  the  oxygen.  The  fre- 
quency of  bubbles  in  each  tube  is 
an  indication  of  the  relative  amounts 
of  starch  manufactured.  Set  the 
tubes  in  the  shade  and  note  the 
effect.  What  do  you  learn  from 
these  experiments  as  to  the  con- 
ditions necessary  to  the  manufac- 
ture of  starch  in  the  leaves  ? 

Nearly  fill  a  glass  funnel  with 
shoots  of  Ceratophyllum,  Myrio- 
phyllum,  or  other  suitable  water  plant,  and  invert  it  in  a  tall 
beaker  of  well  or  spring  water.  The  end  of  the  stem  of  the 
funnel  should  be  submerged  for  an  inch  or  more.  Fill  a 
test  tube  with  water  and  invert  over  the  funnel  (see  Fig.  30). 
Set  the  preparation  in  the  sunlight.  If  the  tube  becomes 
nearly  half  filled  with  gas,  carefully  remove  the  tube  from 
the  funnel,  close  the  tube  tightly  with  the  thumb,  while  its 
mouth  is  kept  submerged ;  turn  its  mouth  upward,  remove 


FIG.  30. 

Device  for  collecting  the  gas 
evolved  by  a  green  plant  un- 
der the  influence  of  the  sun- 
light. See  text. 


8o  Introduction  to   Botany. 

the  thumb,  and  quickly  thrust  a  glowing,  but  not  blazing, 
splinter  into  the  tube.  The  splinter  should  blaze  up,  indi- 
cating the  presence  of  a  large  percentage  of  oxygen. 

91.  Place  a  bell  jar  over  any  plant  of  proper  size  grow- 
ing out  of  doors,  having  first  fitted  a  piece  of  oilcloth,  by 
cutting  a  slit  in  it,  closely  around  the  base  of  the  plant, 
and  having  closed  the  slit  with  vaseline  so  that  the  mois- 
ture from  the  ground  will  be  prevented  from  rising  into  the 
bell  jar.     Set  another  bell  jar  beside  the  first,  on  a  piece 
of  oilcloth,  but  not  over  a  plant.     After  a  time  compare 
the  amounts  of  moisture  which  have  been  condensed  on  the 
inner  surfaces  of  the  jars.     What  does  this  teach  as  to  the 
transpiration  of  water  from  the  leaves  ? 

92.  Mount  a  small  piece  of  a  leaf,  with  the  under  side 
up,  in  chloral  hydrate-iodine  (see  page  381),  and  examine 
with  a  high  power  of  the  compound  microscope.     By  care- 
fully focusing  on  the  upper  surface  of  the  mount,  the  sto- 
mata  (see  page  86),  or  openings  in  the  epidermis,  can  be 
made  out.     They  are  made  conspicuous  by  the  starch  in 
their  guard  cells  being  stained  blue  by  the  iodine,  while 
the  other  cells  of  the  epidermis  are  lacking  in  starch  and 
remain  unstained.     The  opening  between  the  guard  cells 
allows  carbon  dioxide  to  enter  the  leaf  readily,  and  oxygen 
to  pass  out.     It  also  permits  the  water  to  evaporate  from 
the  leaf. 

93.  To   determine  whether  the   stomata  are  necessary 
to  the  ingress  of  sufficient  carbon  dioxide  for  the  manu- 
facture of  starch  within  the  leaf.     Select  a  plant,  such  as 
the  lilac,  whose  leaves   have  stomata  on  the  under  side 
only.     Keep  a  branch  darkened  for  a  day  or  two  or  until 
the  leaves  are  found  destitute  of  starch  by  the  method 
described  in  Observation  89.     Coat  the  under  side  of  some 
of  the  leaves  with  a  melted  mixture  of  equal  parts  of  cocoa 


Leaves.  8 1 

butter  and  wax,  and  expose  the  branch  to  the  sunlight 
until  the  uncoated  leaves  are  found  to  contain  starch. 
Then  test  sections  from  the  coated  leaves,  and  if  these  are 
found  to  be  without  starch,  the  inference  is  well  founded 
that  this  is  due  to  the  exclusion  of  carbon  dioxide  by  the 
closing  of  the  stomata  by  the  wax  mixture. 

94.  Strip  the  leaves  from  some  thrifty  plant,  and  pick 
off  new  leaves  as  fast  as  formed.  Note  the  result,  and  tell 
how  the  final  effect  is  produced. 

DISCUSSION. 

60.  Prominence  of  Leaves.  — We  have  seen  that  as  soon 
as  the  seedling  appears  above  the  ground  its  leaves  unfold 
and  turn  green,  and  that  the  subsequent  development  of 
the  shoot  appears  to  consist  mainly  in  the  production  of  a 
succession  of  green  leaves  arranged  in  a  definite  order  around 
the  stem.     When  we  look  at  a  plant  under  normal  condi- 
tions, in  the  prime  of  its  development,  it  is  the  wealth  of 
its  foliage  which  impresses  us  most.     In  the  whole  family 
of  grass  plants,  with  exceptions  which  do  not  need  to  be 
considered  here,  the  stem  is  very  insignificant  compared 
with  the  leaves.    When  we  contemplate  the  billows  of  leaves 
in  vast  wheat  and  corn  fields,  and  remember  the  rich  har- 
vests that  are  to  follow,  we  must  be  impressed  with  the 
supreme  value  of  leaves  in  the  life  of  the  plant  and  in  the 
production  of  its  seeds.    Under  normal  conditions  of  mois- 
ture, etc.,  we  find  many  plants  without  stems  above  the 
ground,  but  not  without  leaves.     The  superficial  evidence 
is  therefore  plain  that  leaves  are  of  paramount  value  in 
the  economy  of  the  plant.     We  shall  see  how  true  this  is 
when  we  consider  the  work  done  by  them. 

61.  Position   of  the   Leaves. — We  have  observed  that 
the  leaves  are  borne  in  a  definite  order  on  the  stem.     In 


82  Introduction  to  Botany. 

the  lilac  and  horse-chestnut  two  leaves  are  borne  at  the 
opposite  sides  of  each  node,  each  successive  node  having 
its  leaves  at  right  angles  to  those  of  the  node  next  below. 
In  corn  and  other  grasses  the  leaves  are  in  two  opposite 
rows,  only  one  leaf  occurring  at  each  node.  In  the  sun- 
flower there  are  five  rows  of  leaves,  the  rows  being  72° 
apart,  and  each  leaf  142°  from  the  one  next  below  or  above 
it.  Numberless  examples  could  be  brought  forward  to  show 
that  leaves  are  arranged  in  a  definite  order  —  a  fact  which  of 
itself  suggests  that  they  are  important  members  of  the  plant 
body.  Not  only  do  they  have  definite  places  of  origin  on 
the  stem,  but  they  grow  outward  from  the  stem  at  some- 
what uniform  angles  with  the  horizontal —  a  fact  which  may 
suggest  to  the  student  that  they  sustain  important  relations 
with  external  forces. 

62.  Light  Relation  of  Leaves.  — When  we  stand  beneath 
a  tree  we  can  see  that  the  shaded  portion  of  its  crown  does 
not  bear  leaves,  but  only  the  better-lighted  peripheral  por- 
tion. In  carrying  out  Observation  79  we  have  noticed  that 
the  direction  assumed  by  leaves  appears  to  have  some  direct 
relation  to  the  light ;  for  when  the  plant  has  been  illuminated 
more  on  one  side  than  on  another,  the  direction  of  those 
leaves  which  are  still  capable  of  growth  becomes  changed 
so  as  to  expose  their  broad  surfaces  more  nearly  at  right 
angles  to  the  greatest  incident  light.  Our  experiments 
have  taught  us  further  that  starch  is  formed  in  leaves  ex- 
posed to  the  light,  but  not  in  those  kept  in  the  dark.  Finally, 
when  the  leaves  were  stripped  from  a  plant  it  attempted  to 
produce  others,  but,  being  prevented  in  this,  it  died. 

Such  observations  lead  us  to  the  conclusion  that  the  defi- 
nite arrangement  of  leaves  on  the  stem  and  the  more  or 
less  constant  angle  which  they  make  with  the  horizontal  are 
for  the  purpose  of  insuring  that  the  light  shall  be  impeded 


Leaves. 


FIG.  31. 

Mosaic  of  Virginia  Creeper  leaves.  The 
plant  is  climbing  a  wall  and  the  blades 
of  the  leaves  stand  vertically. 


as  little  as  possible  in  reaching  them,  and  that  in  some  way 

the  light  assists  them  in  manufacturing  the  starch  which  is 

an  important  food  of  the 

plant  Having  reached  this 

conclusion,  we  find  it  all  the 

more    interesting    to    note 

how   the   leaves    strive   to 

intercept  the   light   which 

comes  their  way,  and  how 

the  form  and  size  of  the 

plant  and   the   disposition 

and    direction    of    growth 

of   its    branches    are    also 

adapted  to  this  purpose. 

The  same  end  is  attained 
in  various  ways  by  differ- 
ent plants.  When  plants  are  prostrate  on  the  ground  or 
have  grown  up  over  a  wall,  the  leaves  spread  out  more 
or  less  horizontally  in  the 
first  instance,  but  vertically 
in  the  last,  and  intercept 
nearly  all  of  the  light  which 
falls  within  the  radius  of 
the  branches  (see  Fig.  31). 
When  plants  are  upright, 
the  tiers  of  branches  and 
leaves  are  so  separated  that 
the  light  can  strike  between 
them;  when  the  leaves  are 
crowded  together  in  ro- 
settes, the  lower  leaves 
grow  out  beyond  the  upper  ones  and  produce  broad  sur- 
faces only  in  the  exposed  area  (see  Fig.  32);  or,  when  the 


FIG.  32. 

Dandelion  plant  viewed  from  above. 
Leaves  in  rosettes. 


84 


Introduction  to  Botany. 


leaves  are  borne  in  whorls  at  the  nodes,  the  illumination  of 
the  lower  leaves  is  brought  about  by  an  elongation  of  the 
internodes  (see  Fig.  33).  In  short,  after  whatever  plan  the 

plant  may  be  built,  the  exposure 
of  the  leaves  to  the  light  is  always 
provided  for. 

63.  Sun  the  Source  of  Energy. 
—The  sun  is,  of  course,  the  one 
important  source  of  light  which 
reaches  the  earth  from  the  out- 
side universe.  The  heat  and  light 
of  the  sun  are  due  to  the  intense 
energy  of  motion  of  its  mole- 
cules ;  this  is  communicated  to 
the  ether,  which  fills  interplane- 
tary space,  and  in  which  all  ob- 
jects are  embedded.  (We  do  not 
know  what  the  ether  is,  but  there 
are  good  reasons  for  assuming 
its  presence.)  The  ether  trans- 
mits the  motion  communicated 
to  it  by  the  sun  with  such  swift- 
ness that  in  8  minutes  the  dis- 
turbance is  being  felt  on  the 
earth,  having  traversed  a  distance  of  more  than  93  million 
miles. 

The  vibrations  from  the  sun  are  manifest  to  us  as  light 
and  heat.  Those  vibrations  which  give  us  the  sensation  of 
light  succeed  each  other  with  inconceivable  quickness, 
ranging  from  399  million  million  to  750  million  million  per 
second ;  those  of  less  frequency  than  399  million  million, 
while  not  producing  light,  can  be  detected  by  their  heating 
effect.  In  this  way,  vast  amounts  of  energy  are  brought 


FIG.  33. 

Veronica  Virginica,  showing 
leaves  in  whorls  separated  by 
long  internodes.  The  leaves  in 
each  whorl  stand  opposite  the 
interspaces  between  the  leaves  of 
the  next  higher  or  lower  whorl. 


Leaves. 


to  the  earth,  it  being  estimated,  for  instance,  that  when  the 
sun  is  in  the  zenith  the  energy  communicated  by  it  to  the 
earth's  surface  amounts  to  one  horse  power  for  each  area 
five  feet  square.  It  is  impossible  to  conceive  of  the  amount 
of  energy  coming  in  this  way  to  the  leaves  of  plants  over 
the  entire  surface  of  the  earth ;  but  the  student  will  find  it 
instructive  to  estimate  the  amount  for  a  single  definite  field 
of  wheat  or  corn. 

64.  The  Leaf  a  Manufac- 
tory. —  The  leaf  intercepts 
the  sun's  energy  and  is  en- 
abled by  it  to  manufacture 
the  starch  and  other  food 
materials  necessary  to  the 
life  and  growth  of  the  plant. 
We  must  therefore  look  upon 
a  leaf  as  a  manufactory  which 
uses  energy  directly  from  the 
sun  to  do  its  work.  To  use 
economically  the  energy  of 
the  sun  directly  is,  as  yet,  for 


FIG.  34. 


Diagram  showing  the  distance  apart  of 
the  branches  of  vascular  bundles  in 
the  sunflower  leaf,  as  seen  when  look- 
ing through  a  bleached  leaf  with  a 
medium  power.  The  horizontal  line 
shows  A  mm.  magnified  to  the  same 
extent  as  the  figure. 

us  an  unsolved  problem,  but 

plants  have  solved  it  for  themselves.  We  must  examine  the 
construction  of  a  leaf  to  see  how  this  is  accomplished.  We 
note  that  a  typical  leaf  is  spread  out  in  the  form  of  a  flat 
lamina,  which  insures  the  interception  of  a  maximum 
amount  of  light,  and  the  ready  ingress  and  egress  of  gases 
to  and  from  all  parts  of  the  leaf.  We  have  seen  in  Obser- 
vation 87  that  the  vascular  bundles  ramify  throughout  the 
leaf  so  completely  as  to  bring  all  parts  of  it  in  close  com- 
munication with  the  water  brought  up  from  the  roots,  and 
to  quickly  carry  out  of  the  leaf  its  manufactured  products 
(Fig.  34).  And  we  have  further  seen  by  Observation  92 


86 


Introduction  to  Botany. 


that,  while  the  leaf  is  covered  with  an  epidermis  which 
keeps  the  water  from  passing  out  of  it  too  rapidly,  there 
are  openings  in  the  epidermis  (called  stomata ;  singular, 
stoma)  through  which  gases  may  pass  in  and  out.  (See 

Fig.  35-) 

Observations  90  and  93  have  taught  us  that  carbon  diox- 
ide is  necessary  to  the  manufacture  of  starch  by  the  leaf, 

and  that  if  the  stomata  are 
artificially  closed,  starch  can- 
not be  produced,  although  all 
other  conditions  may  be  fa- 
vorable. From  this  we  may 
conclude  that  the  stomata  are 
the  ways  through  which  the 
carbon  dioxide  of  the  atmos- 
phere enters  the  leaf.  Thus 
we  see  the  leaf  is  well  provided 
for  receiving  the  raw  materials 
upon  which  it  must  work.  But 
how  is  the  energy  of  the  sun- 
light employed  in  transform- 
ing the  raw  materials  into  the 
finished  food  product  ? 

If  we  strip  off  a  bit  of  the 

epidermis,  without  bringing  with  it  the  underlying  tis- 
sues, and  hold  it  between  us  and  the  light,  we  see  that  a 
large  percentage  of  the  light  passes  through  it ;  to  such 
an  extent,  in  fact,  that  objects  may  be  seen  through  it. 
This  fact  assures  us  that  the  light  may  pass  freely  into 
the  interior  of  the  leaf.  If  now  we  hold  an  entire  leaf 
between  us  and  the  light,  we  find  that  by  far  the  larger 
part  of  the  light  has  been  absorbed  by  the  leaf ;  in 
other  words,  most  of  the  energy  from  the  sun  which 


FIG.  35. 

Epidermal  cells  with  heavy  outlines. 
The  stomata  are  the  elliptical  bodies 
consisting  of  two  curved  guard  cells 
with  a  narrow  opening  between. 
Ends  of  palisade  cells  of  circular 
outline  are  seen  beneath  the  epider- 
mis. From  leaf  of  Solanum  rostra- 
turn  seen  from  above.  Drawn  with 
a  camera  lucida. 


Leaves.  87 

reaches  the  leaf  has  not  been  transmitted  through  it,  but 
has  been  arrested  within  it  and  transformed  into  some 
other  form  of  energy.  This  has,  in  fact,  taken  place 
within  the  chloroplasts,  which  were  seen  in  Observation  89. 
It  is  the  green  substance,  the  chlorophyll,  which  has  en- 
abled the  chloroplasts  to  accomplish  this.  (See  Fig.  36.) 

65.  Starch  the  First  Visible  Food  Product.  — We  have 
seen  by  Observation  89  that  starch  is  formed  within  the 
chloroplasts,  and  we  must  conclude  that  the  water  from 
the  soil   and   the  carbon  dioxide  of   the  atmosphere   are 
broughtHogether  in  them,  and  that  the  chloroplasts,  em- 
ploying the  energy  of  the  sunlight,  transform  these  sub- 
stances into  the  finished  food  product  in  the  form  of  starch. 
We  know  that  starch  contains  exactly  the  chemical  ele- 
ments furnished  by  water  and  carbon  dioxide,  and   that 
hydrogen  and  oxygen  exist  in  the  same  ratio  in  starch  as 
in  water.     The  chemical  formula  for  starch  is  C6H10O5, 
while  that  of  water  is  H2O,  and  of  carbon  dioxide  CO2. 
The  combination  of  water  and  carbon  dioxide  into  starch 
might  be  expressed  theoretically  in  the  following  formula: 
5  H2O  +  6  CO2  =  C6H10O5  +  6  O2  ;  the  oxygen  being  given 
off  to  the  air  again  through  the  stomata.     Doubtless  the 
process  is  not  as  direct  and  simple  as  this  (it  is  not  definitely 
known  what  the  steps  in  the  process  are),  but  the  equation 
shows  what  excellent  raw  materials  water  and  carbon  diox- 
ide are  for  the  production  of  starch. 

66.  The  Chloroplasts.  — The  chloroplasts  (see  Observation 
89)  are  parts  of  the  protoplast  and  are,  of  course,  alive. 
It  is  their  special  function  to  arrest  the  energy  of  the  sun- 
light, by  means  of  the  chlorophyll  which  they  contain, 
and  employ  it  in  the  manufacture  of  plant  food  from  the 
raw  materials,  carbon  dioxide  and  water.     If  Observations 
89  and  92  are  carefully  made,  it  will  be  seen  that  the 


88 


Introduction  to  Botany. 


chloroplasts  lie  within  cells  and  close  against  their  walls, 
and  that  for  the  circulation  of  air  there  are  spaces  between 
the  cells  which  are  in  communication  with  the  stomata. 
A  reference  to  Fig.  36  will  show  the  relation  of  the 

chloroplasts  to  the  rest 
of  the  leaf  structure. 
The  cells  of  the  upper 
side  of  the  leaf,  termed 
the  palisade  cells,  are  set 
up  in  regular  order  with 
their  long  axes  parallel 
to  the  direction  of  the 
incident  light ;  the  chlo- 
roplasts are  embedded 
in  the  living  substance 
of  the  protoplast  which 
lines  the  cell  walls,  the 
remainder  of  each  cell 
being  filled  with  a  wat- 
ery cell  sap. 

The  palisade  cells  are 
not  compacted  together, 
but  have  air  spaces  be- 
tween them  communicat- 
ing with  the  stomata. 


FIG.  36. 


Cross  section  of  a  leaf.  /,  upper  epidermis ; 
m,  stoma  in  upper  epidermis ;  n,  row  of  pali- 
sade cells  containing  rounded  chloroplasts ; 
i,  lower  epidermis;  k,  stoma  in  lower  epi- 
dermis ;  /,  spongy  parenchyma  cells  contain- 
ing chloroplasts ;  /,  vascular  bundle  in  cross 
section ;  t  and  u,  intercellular  spaces.  After 
SACHS. 


The  more  loosely  ar- 
ranged parenchyma  cells 
on  the  under  side  of  the  leaf,  called  spongy  parenchyma 
cells,  also  contain  chloroplasts,  but  they  necessarily  receive 
less  light  than  those  on  the  upper  side  and  cannot  manu- 
facture so  much  food.  The  vascular  bundles  are  seen  to 
lie  at  the  center  of  the  leaf  where  they  can  readily  com- 
municate both  with  the  palisade  and  spongy  parenchyma 


Leaves. 


89 


cells,  and  so  give  over  to  them  the  water  that  they  bring 
from  the  roots,  and  receive  from  them  the  products  of  their 
manufacture.  Thus  we  see  that  the  leaf  is  in  reality  a 
factory  to  which  the  raw  materials  are  constantly 


FIG.  37. 


the  essential  working  parts  of  a  leaf  and  their  relation  to  each 
->r     !  the  upper  epidermis  containing  one  stoma ;  S,  a  sieve  tube 
'!£•  manufactured  materials  are  removed  from  the  leaf;  r,  a  tra- 
cheal  tub-*,  tr./f>ugh  which  water  is  brought  into  the  leaf;  between  these  tubes 
•iis  four  palisade  cells  are  shown  with  chloroplasts  (rounded, 
m bedded  iiTthe  cytoplasm  lining  their  walls.     The  downward- 
pointing  irrov  ;  indicate  the  light  energy  which  penetrates  to  and  is  absorbed  by 
the  chloroplasis.    The  gas  interchange  of  photosynthesis  and  transpiration  is 
indicated  by  fie  curved  arrows. 


brought,  and  from  which  the  finished  product  is  as  con- 
stantly being  tr?  .  ported.      //* 

67.  Method  of  the  Leaf's  Work. —The  plan  of  the  leaf 
and  the  method  of  its  work  will  be  still  better  understood 
by  reference  to  the  diagram  of  Fig.  37.  For  the  sake  of 
simplicity,  only  a  few  palisade  cells  covered  by  a  small 
portion  of  the  epidermis,  and  a  sieve  tube  and  water  tube, 


Introduction  to  Botany. 


are  represented  in  the  diagram.  The  water  from  the  roots 
ascends  the  water  tubes  and  passes  by  osmosis  into  the 
palisade  cells  and  mingles  with  their  sap.  Since  the  sap 
bathes  the  cytoplasm  which  lines  the  cell  wall,  the  water 
has  easy  access  to  the  chloroplasts  embedded  in  the  cyto- 
plasm (see  page  36).  The  air  with  its  carbon  dioxide 

enters  through  the  sto- 
mata  and  fills  the  spaces 
between  the  palisade 
cells,  and  needs  only  to 
penetrate  through  their 
thin  walls  in  order  to 
come  in  contact  with  the 
chloroplasts.  n 

The  energy  from  the 
sun  is  readily  transmitted 
through  the  epidermis  to 
the  chloroplasts,  and  the 
work  of  food  making  is 
begun.  Under  these  conditions,  the  chlof0p]asts  may  be- 
come filled  with  starch  in  the  course  of  an  hour  (see 
Fig.  38).  The  starch,  which  is  the'  first  food  substance 
formed  that  can  be  detected  by  aid  of  the  microscope,  does 
not  long  remain  in  the  chloroplasts,  but  is  made  soluble, 
mainly  in  the  form  of  glucose  or  grape  sugar ;  and  in  this 
form,  or  in  combination  with  compounds  of  nitrogen  and 
sulphur  to  form  proteids,  it  passes  into  the  sieve  tubes, 
and  is  carried  down  the  stem  and  in  part  into  the  roots, 
or  up  the  stem  where  buds  are  unfolding  or  flowers  and 
fruits  forming,  being  drawn  from  the  sieve  tubes  and 
used  for  food  wherever  it  may  be  needed  throughout  its 
course. 

In  the  night,  when  the  leaf  can  no  longer  obtain  energy 


FTG.  38. 


Cross  -cction  through  leaf  of  Melilotus  alba 
taken  at  sundown.  The  section  has  been 
treated  with  chloral  hydrate  iodine,  .ind  the 
dark  granules  in  the  cells  are  starch. 


Leaves. 


from  the  sun,  the  chloroplasts  cease  to  manufacture  starch, 
and,  gradually  becoming  emptied  of  what  they  contain,  by 
sunrise  may  show  no  further  traces  of  it.  Thus  they  begin 
each  day's  work  unhampered  by  the  products  of  their 
previous  labors  (see  Fig.  39). 

68.  Manufacture  of  Proteids.  —  Starch  and  sugar  repre- 
sent only  one  class  of  food  materials  necessary  to  the 
nutrition  of  plants ;  the 
proteids,  which  contain 
nitrogen  and  sulphur  and 
sometimes  phosphorus 
in  addition  to  the  carbon, 
hydrogen,  and  oxygen 
composing  starch  and 
sugar,  have  yet  to  be 
accounted  for.  Proteids 
can  be  formed  in  any  of 


FIG.  39 


Cross  section  through  leaf  of  Melilotus  alba 
taken  just  before  sunrise,  treated  with  chloral 
hydrate  iodine  and  showing  that  the  starch 
has  been  removed  during  the  night. 


the  living  cells,  and  in 
darkness  as  well  as  in 
light.  They  are  evi- 
dently formed  by  the  cyjtoplasm  of  the  cells  from  the 
elements  of  starch,  combined  with  the  compounds  of  nitro- 
gen, sulphur,  and  often  phosphorus,  which  have  been 
abstracted  from  the  soil  by  the  roots.  Since  their  manu- 
facture can  proceed  in  darkness,  the  energy  for  their 
production  is  evidently  derived  from  the  oxidation  of 
sugar,  and  other  soluble  compounds  obtained  from  the 
starch. 

69.  Transpiration,  and  Evolution  of  Oxygen.  —  Only  a 
small  per  cent  of  the  water  entering  the  palisade  cells  is 
used  in  the  manufacture  of  starch,  the  greater  bulk  of  it 
being  transpired  into  the  intercellular  spaces,  and  passing 
out  of  the  leaf  through  the  stomata.  The  openings  in  the* 


92  Introduction  to  Botany. 

stomata  are  exceedingly  small,  being  only  about  Tf^  milli- 
meter in  diameter  (see  Fig.  35),  but  this  small  size  is  com- 
pensated by  the  great  number  of  the  stomata,  of  which 
there  may  be,  in  different  plants  roughly  estimated,  from 
fifty  to  seven  hundred  in  each  square  millimeter  of  epi- 
dermis. While  the  water  is  thus  evaporated,  the  salts, 
brought  into  the  plant  in  solution  from  the  soil,  are  left  be- 
hind in  a  more  concentrated  solution,  from  which  they  are 
abstracted  as  needed,  in  the  building  up  of  new  compounds. 

Oxygen  is  also  given  off  by  the  leaf,  and,  for  the  most 
part,  doubtless  through  the  stomata;  the  source  of  this 
oxygen  is  the  carbon  dioxide  which  has  been  worked  over 
by  the  chloroplasts,  for  they  use  only  the  carbon,  and  set 
the  oxygen  free.  Thus,  while  the  daylight  is  strong 
enough  to  furnish  the  necessary  energy,  there  is  a  con- 
stant stream  of  carbon  dioxide  into,  and  of  oxygen  out  of, 
the  leaf  ;  so  that  while  the  plant  is  forming  its  food,  — and 
its  food  is  likewise  our  food,  —  it  is  making  the  air  purer 
for  breathing.  The  process  of  starch  formation  by  leaves 
under  the  influence  of  the  sunlight  is  called  photosynthesis 
—  a  putting  together  by  light. 

The  diagram  shown  in  Fig.  42  illustrates  the  mutual 
relations  of  root,  stem,  and  leaf  in  the  absorption,  manu- 
facture, and  translocation  of  materials  needed  by  plants. 

70.  Respiration.  —  After  the  sun  goes  down,  photosyn- 
thesis ceases,  and  another  process  is  found  to  be  going  on 
in  the  leaves ;  that  is,  the  leaves  are  taking  in  oxygen  and 
giving  off  carbon  dioxide  ;  this  they  were  also  doing  dur- 
ing the  daytime,  but  the  oxygen  evolved  by  photosynthesis 
predominates  so  much  that  the  consumption  of  oxygen  at 
that  time  is  obscured.  We  see,  then,  that  the  leaves  are 
taking  in  carbon  dioxide  and  giving  off  oxygen  during  the 
daytime,  and  are  taking  in  oxygen  and  giving  off  carbon 


Leaves.  93 

dioxide  all  of  the  time,  both  day  and  night.  This  latter 
process,  called  breathing  or  respiration,  is  essentially  the 
same  in  plants  as  in  animals,  and  is  as  necessary  to  the  life 
of  the  plant  as  to  that  of  the  animal.  In  the  higher  plants 
the  oxygen  for  respiration  enters  chiefly  through  the  sto- 
mata  and  through  groups  of  loosely  arranged  cork  cells, 
termed  lenticels,  which  break  through  the  epidermis  in 
those  parts  where  cork  is  being  formed  near  the  surface. 
The  lenticels  can  be  seen  to  good  advantage  as  small 
rounded  or  elongated  protuberances  on  many  woody 
branches  a  year  or  more  old.  Since  all  living  cells  must 
respire,  intercellular  spaces  are  provided  in  which  oxygen 
diffuses  throughout  the  plant  body.  In  aquatic  plants 
these  spaces  are  large  enough  to  be  seen  with  the  naked 
eye  (see  the  chapter  on  Adaptation  to  Environment). 
Although  plants  consume  oxygen  in  their  breathing,  they 
give  off  so  much  more  by  the  process  of  photosynthesis 
that  the  net  result  is  a  large  addition  of  free  oxygen  to 
the  atmosphere.  While  the  process  of  respiration  is  com- 
mon to  both  plants  and  animals,  that  of  photosynthesis  is 
peculiar  to  green  plants. 

71.  Supply  of  Raw  Materials.  —  Thus  plants  make  their 
own  food  by  the  wonderful  processes  of  tearing  down  and 
building  up  which  take  place  in  the  chloroplasts.  An  im- 
portant question  in  this  connection  is  whether  there  is 
an  unlimited  amount  of  raw  materials  at  their  disposal. 
Water  certainly  seems  unlimited  for  the  larger  part  of  the 
earth's  surface.  The  necessary  salts  occurring  in  naturally 
rich  soils  are  also  practically  inexhaustible,  although  they 
may  not  become  soluble  rapidly  enough  to  satisfy  all  the 
demands  of  agriculture.  Carbon  dioxide  occurs  in  the 
atmosphere  in  very  small  percentage,  namely,  between 
three  and  four  parts  in  ten  thousand  of  the  atmosphere ; 


94  Introduction  to  Botany. 

and  although  it  is  employed  by  plants  in  making  their  food, 
it  is  constantly  being  replenished  by  the  breathing  of  ani- 
mals and  plants,  by  the  disintegration  of  plant  and  animal 
remains,  by  volcanic  activity,  and  by  the  burning  of  wood 
and  coal.  Since  carbon  dioxide  exists  in  such  small  per- 
centage in  the  atmosphere,  vast  amounts  of  the  latter  must 
be  sifted  by  the  leaf  before  sufficient  carbon  can  be  ob- 
tained to  build  the  body  of  a  good-sized  plant.  A  tree 
having  a  dry  weight  of,  say,  five  thousand  kilograms  would 
contain  twenty-five  hundred  kilograms  of  carbon,  and  to 
obtain  this,  twelve  million  cubic  meters  of  air  must  have 
been  deprived  of  carbon  dioxide.  The  spaces  between  the 
cells  of  the  palisade  and  spongy  parenchyma  allow  a  broad 
expanse  of  free  cell  surface  for  the  absorption  and  giving 
off  of  gases,  the  free  surfaces  acting  much  as  do  the  gills 
of  a  fish  in  absorbing  the  small  percentage  of  oxygen  from 
the  water. 

72.  Action  of  the  Stomata.  —  When  there  is  sufficient 
light  to  enable  the  chloroplasts  to  do  their  work,  there 
being  at  the  same  time  plenty  of  water  in  the  soil  to  satisfy 
the  demands  from  the  leaf,  the  stomata  stand  wide  open 
(Fig.  40,  a)  and  permit  the  ingress  of  carbon  dioxide ;  but 
if  the  water  supply  is  running  low  so  that  the  plant  is  in 
danger  of  drying  up,  the  stomata  close  (Fig.  40,  b\  even 
when  the  leaf  is  well  illuminated.  The  stomata  as  a  rule 
close  in  darkness,  but  rather  from  physical  than  physio- 
logical reasons.  The  conditions  governing  the  action  of 
the  stomata  appear  to  be  about  as  follows :  when  the  leaf 
is  illuminated,  the  chloroplasts  in  the  guard  cells  manufac- 
ture substances  which  become  dissolved  in  the  cell  sap, 
and  so  alter  its  density  and  constitution.  This  results  in 
an  osmotic  inflow  from  the  neighboring  tissues,  which  in- 
creases the  turgidity  of  the  guard  cells,  causing  them  to 


Leaves. 


95 


stretch  and  spread  apart;  but  in  the  nighttime  the  chlo- 
roplasts  of  the  guard  cell  no  longer  manufacture  new 
material ;  the  cells  accordingly  lose  their  turgidity  and  are 
drawn  together  again  by  the  elasticity  of  their  walls  (see 
Fig.  40). 

When  the  soil  is  dry,  and 
the  amount  of  water  rising 
from  the  roots  is  much 
reduced,  the  guard  cells 
probably  lose  water  faster 
than  they  are  able  to  draw 
it  from  surrounding  tissues, 
and  so  are  incapable  of  ac- 
quiring the  degree  of  tur- 
gidity necessary  to  their 
opening.  From  such  simple 
causes  as  these,  the  plant 
may  allow  the  ingress  of 
carbon  dioxide  when  the 
conditions  are  such  that  it 
can  be  employed  in  food 
making,  and  may  guard 
against  too  great  loss  of  water  when  the  supply  of  it  is 
scarce. 

73.  The  World's  Food  Supply.  —  When  we  consider  pho- 
tosynthesis from  the  standpoint  of  the  world's  food  supply, 
it  becomes  a  subject  of  supreme  interest.  The  entire 
substance  of  seeds,  tubers,  bulbs,  and  roots,  which  directly 
or  indirectly  constitute  the  food  of  mankind,  was  only 
a  few  months  past  scattered  in  -the  form  of  water,  soil 
particles,  and  gases  of  themmosphere,  no  amounts  of  which 
could  keep  the  world  from  starvation  ;  and  the  continuance 
of  animal  life  has  be&n  made  possible  only  through  the 


FIG.  40. 

a,  surface  view  of  an  open  stoma;  £, 
surface  view  of  a  closed  stoma  (after 
HANSEN)  ;  c,  diagram  of  a  transverse 
section  of  a  stoma.  The  light  lines  in- 
dicate the  closed  position  of  the  guard 
cells  and  the  heavy  line  the  open  posi- 
tion (after  SCHWENDENER). 


96  Introduction  to  Botany. 

intervention  of  plants.  The  starch  and  proteids  stored  up 
in  seeds,  and  particularly  in  the  grains  of  cereals,  are  in 
quite  stable  condition,  and  are  well  adapted  to  carry  plant 
life  through  months  and  even  years  of  adverse  conditions. 
Their  stability  and  condensed  condition  also  make  them 
fit  for  the  food  of  mankind  through  the  months  between  har- 
vests and  through  years  of  famine.  It  is  this  stable  and 
condensed  form  which  enables  cereals  to  be  transported  to 
all  quarters  of  the  globe  so  that  the  people  of  one  conti- 
nent may  be  fed  from  the  granaries  of  another. 

74.  Amount  of  Work  done  by  Leaves.  —  The  amount  of 
work  done  by  the  leaves  of  plants  in  a  single  year  over 
the   entire   earth's   surface   is   beyond   computation ;    but 
perhaps  some  idea  of  its   immensity  may  be   gained   by 
calling  to  mind  that  in  the  state  of  Kansas  alone,  in  the 
year    1900,    over  134  million   bushels   of   corn    and   over 
77  million  bushels  of  wheat  were  harvested.     Or,  to  take 
examples  with  smaller  numbers,  it  has  been  estimated  that 
one  square  meter  of  sunflower  leaf  may,  in  a  single  summer 
day,  produce  twenty-five  grams  of  starch,  and  a  single  stalk 
of  corn  may  in  the  same  time  send  out  into  the  ears  from 
ten  to  fifteen  grams  of  reserve  food  material. 

75.  Duration  of   Work  of  Leaves.  —  In  some   kinds   of 
plants,  such  as  tulips,  peas,  wheat,  and  corn,  the  leaves 
finish  their  work  before  the  close  of  the  growing  season 
and  die,  having  first  given  over  to  the  seeds,  bulbs,  etc., 
most  of  their  materials  which  could  be  used  as  reserve 
food.     In  other  plants,  such  as  our   common   trees   and 
shrubs,  the  leaves  continue  their  work  until  the  close  of 
summer.     They  then  send  over  to  the  body  of  the  plant, 
which  is  to  survive  the  winter,  much  of  the  useful  material 
contained  in  them ;    and  then  sever  themselves  from  the 
branches  by  producing  a  layer  of  delicate  tissue,  so  that 


Leaves.  97 

they  become  torn  away  by  their  own  weight,  or  are  easily 
blown  off  by  the  wind.     The  separating  layer  of  tissue  is 
often  of  the  nature  of  cork  and  then  serves  also  to  heal 
the  wound.     In  evergreens,  however,  the  leaves  may  re- 
main on  the  branches  for  several  years.     Figure  41  shows 
a  branch  of  pine  bearing 
leaves  some  of  which  are    ' 
three  years  old. 

The  fall  of  the  leaf  is  a 
wise  provision  for  the  con-    i 
ditions  of  winter.     When 
the  ground  is  very  cold  or 
frozen,  the  roots  are  no    ' 

longer    able     to     absorb 

FIG.  41. 
water  from  the  soil,  and 

......  .   .          Branch  of  Pine  tree  bearing  leaves  three  years 

it     the     broad    transpiring       old.    There  are  gaps  between  the  leaves  of 

surfaces  of  the  leaves  re-      each  year>s  srowth  where  the  bud  scales 

were 

mained,  the  plant  would 

suffer  from  too  great  loss  of  water ;  the  weight  of  the  snow 
also  which  would  accumulate  on  the  leaves  would  break 
the  branches,  as  may  sometimes  be  observed  when  early 
snows  overtake  the  trees  with  their  leaves  still  on. 

76.  Size  and  Form  of  Leaves.  —  Leaves  show  great  varia- 
tion in  size  and  form.  The  leaves  of  mosses,  for  instance, 
are  only  a  few  millimeters  in  length  and  breadth,  while 
those  of  the  palm  Raphia  tcedigera,  growing  in  Brazil, 
have  petioles  from  four  to  five  meters  long  and  leaf-blades 
from  nineteen  to  twenty-two  meters  long  and  twelve  meters 
broad.  The  student  can  at  any  time  during  the  growing 
season  find  endless  materials  for  the  study  of  variations  in 
leaf  forms.  We  should  not,  however,  look  at  the  differ- 
ences in  leaf  forms  as  expressions  merely  of  the  power  to 
vary,  for  we  may  find  that  the  form  of  the  leaf  is  nicely 


98  Introduction  to  Botany. 

adjusted  to  its  size,  position  on  the  stem,  and  the  habit  and 
habitat  of  the  plant.  Indeed,  it  may  be  taken  for  granted 
that  any  member  of  an  organism  so  important  to  the  life 
of  the  individual  and  the  continuance  of  the  species  as  the 
leaf  is  would  not  be  apt  to  show  marked  variations  not  in 
some  way  correlated  with  its  functions. 

77.  Characterization  of  Leaves.  —  While  the  leaf  is  an 
outgrowth  from  the  stem  it  does  not  grow  indefinitely  as 
stems  do,  but  soon  attains  its  maximum  size.  It  seems 
impossible  to  formulate  a  definition  that  will  clearly  apply 
to  all  leaves ;  as  a  general  characterization  we  might  say, 
however,  that  leaves  are  lateral  outgrowths,  having  buds 
or  branches  in  their  axils,  arising  in  definite  succession  on 
a  stem,  limited  in  growth,  and  having  for  their  chief 
function  the  manufacture  of  the  plant's  food.  * 


Chief  functions  of  the  leaf: 
Photosynthesis. 
Absorption  of  gases. 
Absorption  of  the  sun's  energy. 
Transpiration. 


Absorbed  by  the  leaf: 
Sun's  energy. 
Oxygen  for  respiration. 
Carbon  dioxide  for  photosynthesis 


Given  off  from  the  leaf: 
Oxygen  from  photosynthesis. 
Carbon  dioxide  from  respiration. 
Water  by  transpiration. 


Important  functions  of  the 
leaf  in  common  with  other 
plant  parts: 

Synthesis  of  proteids. 

Respiration. 

Digestion. 


Absorbed  by  the  roots : 

Oxygen. 

Water. 
Salts  of: 

Potassium. 

Calcium. 

Magnesium. 

Iron. 

Nitrogen. 

Sulphur. 

Phosphorus. 


Given  off  from  the  roots : 
Carbon  dioxide.     Possibly  in  some  ir 
stances  organic  acids  and  enzymes. 


FIG.  42. 

Longitudinal  diagram  of  the  vegetative  parts  of  a  plant,  with  special  reference  to  the 
absorption  and  translocation  of  materials.  *  In  this  diagram  the  dotted  highway  is 
the  water-conducting  area  (xylem  portion  of  vascular  bundle),  and  the  black  highway 
(phloem  portion  of  the  vascular 'bundle)  is  the  area  for  conduction  of  the  food  made 
in  the  leaf.  The  arrows  indicate  the  direction  of  flow  in  these  highways. 


CHAPTER   VI. 

GROWTH  AND  MOVEMENT. 

PROVIDING   MATERIALS. 

For  most  of  the  following  observations,  plants  growing  under  natural 
conditions  out  of  doors  are  to  be  employed.  Only  those  plants  should 
be  selected  which  are  thrifty  and  in  a  growing  condition.  In  obtaining 
root  tips  of  onion,  place  the  bulbs  on  moist  carpet  or  blotting  paper, 
and  cover  with  a  bell  jar.  When  the  roots  have  grown  out  about  T36  of 
an  inch,  cut  them  off  with  a  sharp  knife  and  place  them  in  a  i  %  solu- 
tion of  chromic  acid  in  water  for  48  hours  ;  then  wash  in  running  water 
for  half  a  day,  and  place  in  20  %  alcohol  for  a  few  hours,  and  for  the 
same  length  of  time  in  50  %  alcohol,  and  finally  in  70  %  alcohol.  After 
being  prepared  in  this  way  the  roots  may  be  kept  indefinitely  in  equal 
parts  of  alcohol,  glycerine,  and  water. 

Good  sections  for  our  present  purpose  can  be  obtained  by  embedding 
the  roots  in  elder  pith,  and  making  longitudinal  sections  free-hand  with 
a  sharp  razor  (see  page  377).  Thin  median  sections  should  be  stained 
in  a  solution  of  Safranin  (see  page  388),  and  mounted  for  examination 
in  dilute  glycerine.  There  are  more  elaborate  methods  for  preparing 
uniformly  thin  sections  by  embedding  the  material  in  paraffin,  and  cutting 
the  sections  with  a  microtome  (see  pages  383  and  386),  but  these  methods 
are  not  necessary  for  this  study,  since  a  few  good  sections  may  serve  for 
demonstration  to  the  entire  class. 

In  selecting  stamen  hairs  of  Tradescantia,  only  those  should  be  chosen 
whose  cell  sap  is  still  colorless.  These  hairs  of  different  ages  might  be 
used  in  place  of  sections  from  the  onion  root  tip,  but  they  are  not  so 
satisfactory  as  well-prepared  sections. 

It  is  a  simple  matter  to  grow  seedlings  of  the  sensitive  plant,  Mimosa 
pudica,  in  pots  under  bell  jars.  The  soil  should  be  a  mixture  of  equal 
parts  of  rich  garden  soil,  sifted  sand,  and  well-rotted  manure.  The  pots 
should  be  kept  in  a  warm  place,  and  as  soon  as  the  seedlings  appear, 
the  bell  jars  should  be  raised  at  one  side.  The  pots  should  be  kept 
well  watered. 

100 


Growth  and  Movement. 


101 


OBSERVATIONS. 

95.  With  waterproof  India  ink  make  marks  two  millime- 
ters apart  on  some  rapidly  growing  stem,  beginning  at  the 
apex  and  extending  downward  for  several  internodes.    Ob- 
serve from  time  to  time  whether  the  marks  become  sepa- 
rated farther  by  the  elonga- 
tion of  the  stem,  and  whether 

growth  seems  to  be  more  rapid 
in  one  region  than  in  another. 
Where  does  growth  in  length 
seem  to  have  ceased?  Com- 
pare with  similar  observations 
on  the  growth  of  roots. 

96.  By  means  of  the  simple 
apparatus  illustrated  in  Fig. 
43  observe  the  rate  of  growth 
of  some  rapidly  growing  stem. 
Compare  the  amount  of  growth 
in  the  daytime  with  that  for 
the  same  number  of  hours  in 
the  nighttime. 

97.  By  means  of  recorded 
measurements,    compare    the 
rate  of  "growth  of  two  plants 

of  the  same  kind,  one  of  which  is  in  a  dry  soil,  and  the 
other  under  the  same  conditions,  with  the  exception  that  it 
is  kept  well  supplied  with  water.  What  conclusion  do  you 
reach  as  to  the  use  of  water  in  growth  ? 

98.  Cover  one  shoot  of  a  plant  which  branches  near  the 
ground  (such  as  the  potato)  with  something  to  exclude  the 
light,  and  leave  the  remaining  shoots  uncovered.     After  a 
few  days  compare  the  lengths  of  the  newly  formed  inter- 


FTG.  43. 

A  simple  form  of  Auxanometer.  A 
thread  is  attached  to  the  apex  of  the 
plant  and  passed  over  the  pulley  and 
held  taut  by  a  weight  which  is  only 
heavy  enough  to  move  the  pointer  as 
the  plant  elongates.  The  arc  can  be 
made  of  heavy  manila  paper  and  all 
other  parts  of  light  wood. 


102 


Introduction  to  Botany. 


nodes  of  the  shaded  and  unshaded  shoots,  and  also  the 
sizes  of  the  leaves  formed  after  the  experiment  was  started. 
What  is  the  effect  of  absence  of  light  on  the  growth  of 
stems  and  leaves  ? 

99.  Plant  some  seeds  of  Indian  corn  and  garden  bean 
in  moist  sawdust  contained  in  a  wire  basket,  which  should 
be  inclined  as  shown  in  Fig.  44.  Keep  the  sawdust  moist, 
and  note  the  direction  taken  by  the  roots  after  they  have 

grown  down  through  the  meshes 
of  the  wire  at  the  bottom.  What 
does  this  experiment  teach  as  to 
the  probable  behavior  of  roots 
under  natural  conditions  ? 

100.  Bend  over  a  vertical  shoot 
of  some  thrifty  plant,  and  fasten 
it  down  in  such  a  way  as  to  allow 
freedom  of  action  toward  the  apex. 
Observe  the  position  finally  taken 
by  the  stem  and  leaves.  How  do 
FIG.  44.  you  account  for  the  change  of 

Experiment  to  show  hydrotropism     position  observed,  and  what  is  its 


of  roots.    After  SACHS. 


use 


101.  Shade  a  plant  so  that  it  receives  light  on  one  side 
only.     How  do  the  leaves  and  stems  behave,  and  to  what 
purpose  ?     Remove  the  screen  after  a  marked  change  has 
been   noticed,  and   note  whether   the   different   members 
assume  their  former  positions. 

1 02.  Invert  a  plant  and  notice  the  direction  taken  by  its 
growing  members.     Do  those  parts  which  have  ceased  to 
grow  change  their  positions  ?     After  a  day  or  so  set  the 
plant  upright  and  note  whether  the  parts  come  back  to 
their  original  positions. 

103.  Observe   the   behavior  of   the   tendrils   of   plants 


Growth  and  Movement.  103 

growing  under  normal  conditions  out  of  doors.  Try  to 
determine  what  incites  some  tendrils  to  twine,  and  why 
the  tendrils  of  Virginia  creeper  grow  toward  a  support. 
Gently  rub  the  tendrils  of  squash  or  wild  cucumber  on  one 
side  with  a  stick  and  watch  for  the  result.  Inclose  some 
young  shoots  of  Virginia  creeper  so  that  they  are  kept 
dark,  and,  after  new  tendrils  have  been  formed  under  these 
conditions,  note  whether  they  grow  in  a  different  direction 
from  that  taken  by  tendrils  which  have  developed  under 
normal  conditions  of  illumination. 

104.  Note   the   positions    of    leaves   of   clover,    Oxalis, 
Amorpha,  etc.,  in  the  daytime  and  in  the  nighttime.     Of 
what  use  are  the  observed  changes  in  position  ? 

105.  Observe  the  direction  taken  by  the  stems  of  trumpet 
creeper.      Is   there   any  difference   in   behavior   between 
those  stems  which  bear  leaves  only  and  those  which  bear 
flowers  as  well  as  leaves  ? 

1 06.  Grow  in  a  greenhouse  or  under  a  bell  jar  seedlings 
of  Mimosa  pu^ica,  and  note  the  effect  of  touching  the  leaf- 
lets, or  of  shaking  the  entire  plant.    Do  the  leaflets  change 
their  position  on  being  transferred  from  sunlight  to  shade, 
and  vice  versa  ?     Do  they  have  distinct  positions  for  night- 
time and  daytime  ?     Of   what  use  to  the  plant  are  the 
actions  observed  ? 

107.  Mount  a  young  stamen  hair  of  Tradescantia   Vir- 
ginica,  or  hairs  from  young  portions  of  the  stem  of  tomato 
or  squash,  in  a  drop  of  water  on  a  glass  slip,  and  examine 
under  high  power  of  the  microscope  for  streaming  motion 
of  the  cytoplasm.     In  removing  hairs,  some  of  the  tissue 
to  which  they  are  attached  should  be  taken  with  them  in 
order  to  prevent  their  injury. 

1 08.  Cut  a  hole  a  trifle  smaller  than  a  coverglass  in  a 
piece  of  thick  felt  paper  one  inch  square.     Boil  the  paper 


IO4  Introduction  to  Botany. 

for  a  short  time  in  water,  and  place  it  at  the  center  of  a 
glass  slip.  Place  at  the  center  of  a  coverglass  a  small  bit 
of  rotting  wood  or  bark  on  which  is  growing  a  slime  mould 
plasmodium  (see  page  252).  The  piece  of  wood  or  bark 
should  be  so  small  that  it  will  cling  to  the  coverglass  by 
its  own  moisture.  Put  the  coverglass  with  the  object  down- 
ward over  the  hole  in  the  felt  paper,  and  set  the  prepara- 
tion over  a  tumbler  of  water  under  a  bell  jar  so  that  it  will 
not  become  dry.  If  the  experiment  is  successful,  the  plas- 
modium will  grow  out  over  the  coverglass,  and  may  be 
studied  by  transmitted  light  under  high  powers  of  the 
microscope.  Make  notes  on  the  streaming  of  the  proto- 
plasm. The  batter  like  plasmodium  can  be  found  at  almost 
any  season  of  the  year  under  the  bark  of  moist  logs  or  on 
decaying  leaves  which  have  gathered  to  some  depth  in 
damp  woods. 

DISCUSSION. 

78.  The  Plant  Cell.  —  When  we  examine  very  thin  sec- 
tions of  the  growing  root  tip  of  onion,  for  instance,  under 
a  high  magnifying  power,  we  find  that  they  are  composed 
of  very  small  compartments,  those  near  the  apex  being 
very  nearly  isodiametric,  while  those  farther  back  are  more 
or  less  elongated  (Fig.  45,  A  and  B}.  If  we  were  able  to 
see  through  a  whole  root  tip  magnified  to  the  same  extent, 
we  should  find  that  each  of  these  compartments  is  really  a 
closed  box  to  which,  including  its  living  contents,  the  term 
cell  has  been  applied.  The  walls  of  the  cells  of  the  onion 
root  tip  are  composed  of  cellulose,  a  substance  well  suited 
to  form  the  walls  of  growing  cells,  for  it  can  stretch  and 
allow  the  cells  to  enlarge,  and  it  permits  liquids  and  gases 
in  solution  to  pass  through  it  readily.  It  is  not  alive,  but 
has  been  manufactured  by  the  live  parts  of  the  cell.  The 


Growth  and  Movement. 


105 


live  part  of  the  cell  consists  of  the  cytoplasm,  a  proto- 
plasmic structure  which  occupies  most  of  the  cell  cavity  of 
young  cells ;  the  nucleus,  which  is  suspended  centrally  in  the 
cytoplasm  in  young  cells,  but  as  the  cell  grows  older  may 
have  a  lateral  position 
(Fig.  45);  the  leucoplasts, 
small  dense  bodies  which 
multiply  by  division  and 
have  special  functions  re- 
counted in  the  next  para- 
graph; and  the  plasma 
membrane,  a  special- 
ized part  of  the  cyto- 
plasm which  lines  the 
cell  wall.  (See  Fig.  12 
for  details.) 

79.  Functions  of  Cell 
Organs.  —  The  plasma 
membrane,  cytoplasm, 

leUCODlastS,  and  nucleus    A>  longitudinal  section  through  the  root  tip  of 

an  Onion  ;  B,  successively  older  cells,  i,  from 
Constitute    the    live    part       immediately  back  of  the  root  cap  where  cell 

of  the  cell,  and  whatever      d,jvision  «  g°inf  on:  2  an£  3,  older  ceils, 

showing  the  modifications  which  I  undergoes 

is    done   by  the    plant   as        with  age.     In  i  the  cytoplasm  fills  the  cell 
i  •    •          -i      j       •  cavity  and  the  nucleus  is  relatively  large.   The 

a  living  body  is  accom-      few  hyeavy  points  indicate  leucopksts 
plished  by  one  or  more 

of  these  live  parts  or  organs  of  the  cell,  which  collectively 
are  termed  the  protoplast.  We  have  noticed  in  our  study 
of  roots  that  it  is  the  plasma  membrane  which  determines, 
to  some  extent,  whether  certain  substances  shall  pass  to  or 
from  the  interior  of  the  cell.  It  seems  to  be  the  guardian 
of  the  cell  and  the  inspector  of  all  material  interchanges. 
It  appears  also  to  build  the  cell  wall,  and  there  is  evidence 
to  show  that  it  is  the  receiving  organ  for  stimuli  from  the 


FIG.  4S. 


106  Introduction  to  Botany. 

outside  world  —  light,  heat,  gravity,  mechanical  impact, 
etc.,  being  probably  first  perceived  and  communicated  by 
it  to  the  other  organs  of  the  cell. 

TJie^cytoplasm  is  the  medium  of  interchange  of  stimuli 
between  the  plasma  membrane  and^the  nucleusj  it  prob- 
ably manufactures  various  nitrogenous  food  materials  from 
substances  furnished  it  by  the  chloroplasts,  and  from  salts 
of  nitrogen,  sulphur,  and  phosphorus,  which  have  come 
up  from  the  soil.  It  appears  to  have  something  to  do  with 
the  production  of  ferments  which  render  the  reserve  food 
materials  more  soluble  and  diffusible ;  it  is  probably  con- 
cerned with  manifold  changes  of  a  chemical  nature  which 
are  constantly  taking  place  within  the  cell;  and  it  con- 
tributes some  of  its  own  substance  toward  the  production 
of  certain  fibrillar  structures  which  assist  in  nuclear  and 
cell  division. 

The  leucoplasts  have  the  power  of  forming  starch  from 
materials  which  come  to  them  from  the  leaves ;  or  when 
they  are  exposed  to  the  light  they  may  produce  chlorophyll 
within  themselves,  and  become  chloroplasts ;  or  they  may 
produce  other  coloring  substances  than  green,  as  seen  in 
certain  flowers  and  ripening  fruits,  and  then  they  are  termed 
chromoplasts.  Leucoplasts,  chloroplasts,  and  chromoplasts 
collectively  are  called  plastids. 

To  the  nucleus,  in  particular,  is  intrusted  the  very  impor- 
tant function  of  bearing  and  bequeathing  from  generation 
to  generation  the  inheritable  qualities.  That  the  embryo 
in  an  acorn  shall  develop  into  an  oak  instead  of  into  an- 
other kind  of  plant  depends  in  large  measure  on  the  nuclei 
in  the  cells  of  the  embryo.  The  nuclei,  as  the  bearers  of 
the  inheritable  qualities,  must  determine  how  the  cells  shall 
behave  under  varying  conditions.  The  nucleus  has  to  do 
also  with  processes  involving  chemical  changes,  such  as  the 


Growth  and  Movement.  107 

formation  of  starch  and  proteids,  the  production  of  secre- 
tions, the  growth  of  plasma  membrane,  and  building  of 
cell  wall.  While  it  is  not  absolutely  known  that  the  parts 
of  the  cell  have  the  distinct  functions  here  assigned  to 
them,  yet  the  circumstantial  evidence  that  they  do  amounts 
almost  to  proof. 

We  find,  then,  that  we  may  look  upon  the  living  cells 
of  the  plant  body  not  only  as  units  of  structure,  like  the 
bricks  of  a  house,  b,ut  as  centers  of  vital  activity  which 
induce  and  regulate  whatever  the  plant  does. 

80.  Advantages  of  Cellular  Structure.  —  The  construction 
of  the  plant  body  from  many  small  cells  has  certain  distinct 
advantages :  it  renders  the  body  stronger,  lessens  liability 
to  fatal  injuries,  and  makes  division  of  labor  possible,  so 
that  one  part  of  the  body  may  protect  the  other  parts; 
one  part  may  give  strength  to  the  whole  body,  while  other 
parts  may  be  adapted  for  transporting  or  manufacturing 
materials,  etc.     Thus  the  business  of  the  plant  is  economi- 
cally and  efficiently  carried  on. 

81.  Continuity  of  Living   Substance. — While   the   live 
part  of  the  plant  body  seems  to  be  divided  by  the  cell 
walls  into  numberless  units,  it  is  probable  that  these  are 
united  by  minute  strands  of  living  substance,  which  are 
difficult  of  demonstration  by  means  of  the  microscope; 
their  existence,  however,  has  actually  been  demonstrated 
in  many  cases.     We  are  justified  in  the  conception  that 
the  whole  live  body  of  the  plant  stands  united  by  living 
substance,  from  the  farthest  roots  to  the  remotest  buds, 
although  apparently  severed  by  numberless  cell  walls. 

82.  Cell  Division.  —  Tne  enlargement  of  the  plant  body 
depends  upon  the  multiplication  and  enlargement  of  its 
cells.     Multiplication  of  the  cells  is  brought  about  by  their 
division,  one  cell  becoming  two  by  the  formation  of  a  new 


io8  Introduction  to  Botany. 

partition  wall,  and  so  on.  In  this  process  the  parent  cell 
must  distribute  to  the  two  daughter  cells  resulting  from  its 
division  all  of  the  qualities  and  powers  possessed  by  itself ; 
and  to  accomplish  this  it  is  important  that  the  division  of 
the  nucleus  in  particular  should  be  equal,  one  daughter 
cell  receiving  neither  more  nor  less  than  the  other.  We 
are  able  to  see,  in  following  the  steps  in  the  division  of  a 
cell,  that  the  equal  partition  of  the  nucleus  is  actually 
accomplished  with  astonishing  care  (see  Fig.  46). 

The' nucleus  becomes  threadlike  in  structure  (i);  the 
thread  is  divided  longitudinally  through  the  middle,  and 
then  the  double  thread  is  broken  transversely  into  several 
double  rods  (2);  the  double  rods  are  now  grouped  at  the 
equator  of  the  cell,  namely,  at  the  central  plane,  where  the 
dividing  wall  is  to  be  formed  (3  and  4) ;  then  the  two  halves 
of  each  double  rod  are  drawn  apart  to  opposite  poles  of  the 
mother  cell  (5,  6,  and  7),  where  they  fuse  together  to  form 
two  daughter  nuclei  (8).  Finally  a  wall  is  formed  which 
cuts  the  mother  cell  into  two  daughter  cells  (8  and  9).  This 
will  serve  as  a  general  statement,  but  the  details  of  the 
process  are  so  wonderful  that  they  have  been  given  more 
fully  in  the  description  of  the  figure. 

If  we  go  back  to  the  beginning  in  the  life  history  of  one 
of  the  higher  plants,  we  find  that  it  is,  at  first,  a  fertilized 
egg  cell,  of  which  we  shall  learn  more  in  the  chapter  on 
the  flower.  The  plant  has,  therefore,  its  beginning  in  a 
single  minute  cell ;  this  divides,  and  its  offspring  in  their 
turn  divide,  until  the  whole  plant  body,  consisting  of  mil- 
lions of  cells,  is  formed  by  its  descendants. 

83.  Cell  Growth.  —  After  the  cells  have  divided,  the 
daughter  cells  increase  in  size,  and  not  till  then  does  an 
enlargement  of  the  plant  take  place.  The  increase  in  size 
of  the  cells  is  brought. about  by  absorption  of  water  until 


Growth  and   Movement. 


109 


8 
FIG.  46. 


Diagrammatic  representation  of  Nuclear  and  Cell  Division. 

1.  A  cell  with  resting  nucleus  just  previous  to  division.   The  cytoplasm  (stippled) 
fills  the  cell  cavity.    The  nuclear  thread  is  shown  as  a  tortuous  band  throughout  the 
nucleus;  the  black  body  in  the  nucleus  is  the  nucleolus. 

2.  The  nuclear  membrane  and  the  nucleolus  have  disappeared,  the  nuclear 
thread  has  become  divided  transversely  into  distinct  bodies  termed  chromosomes, 
and  these  are  seen  to  be  divided  longitudinally. 

3.  The  chromosomes  have  become  lined  up  at  the  equator  of  the  cell  and  pro- 
toplasmic threads  converge  from  them  toward  opposite  poles. 

4.  The  same  as  3  seen  from  one  of  the  poles. 

5.  The  longitudinal  halves  of  the  chromosomes  are  moving  toward  opposite 
poles.  ^ 

6.  A  later  stage,  showing  connecting  protoplasmic  threads  between  the  receding 
chromosomes. 

7.  The  chromosomes  arrived  at  the  opposite  poles  are  fusing  together  end  to 
end  to  form  nuclear  threads. 

8.  The  nuclear  threads  have  assumed  the  form  of  two  daughter  nuclei,  nucleoli 
have  appeared,  the  connecting  threads  have  spread  from  wall  to  wall,  and  a  new 
cell  wall  dividing  the  mother  cell  in  halves  is  being  formed,  apparently  by  the  con- 
necting threads. 

9.  A  nuclear  membrane  has  been  formed  about  the  daughter  nuclei,  the  con- 
necting threads  have  disappeared,  and  nuclear  and  cell  division  is  completed. 


no  Introduction  to  Botany. 

the  walls  become  stretched,  by  the  laying  down  of  new 
materials  in  and  about  the  walls,  and  by  the  addition  of 
appropriate  materials  to  the  different  parts  of  the  proto- 
plast. The  addition  to  the  cell  wall  is  evidently  accom- 
plished by  the  plasma  membrane,  while  each  part  of  the 
protoplast  is  presumably  capable  of  assimilating  materials 
for  itself.  We  see  how  necessary  water  is  to  growth,  not 
only  in  giving  up  its  hydrogen  and  oxygen  for  the  manu- 
facture of  plant  substance,  or  in  acting  as  a  solvent,  but  in 
supplying  the  necessary  stretching  force  which  initiates  the 
first  step  in  increase  in  size. 

84.  Changes  in  Character  of  Cells.  —  As  the  cells  attain 
their  definite  size  and  form,  we  find  that  they  do  not  all 
behave  in  the  same  manner,  although  they  have  all   de- 
scended from  a  common  parent  cell.     Some  become  long 
and  fibrous,  while  others  remain  nearly  isodiametric ;  some 
fuse  end  to  end  to  form  water  tubes,  while  others  infiltrate 
their  walls  with  waxy  substances  to  keep  water  from  pass- 
ing through  them.    The  cells  have  come  to  act  so  differently 
because  they  have  been  under  different  conditions.     Those 
which  are  on  the  outside  exposed  to  the  air  have  not  the 
same  surroundings  as  those  which  lie  at  the  interior,  and 
the  various  zones  of  interior  cells  are  under  different  con- 
ditions of  exposure  to  air,  and  of  tension,  pressure,  etc. 
Thus  the  unlike  action  of  cells  which  have  descended  from 
a  common  ancestor  may  be  in  part  acounted  for. 

85.  Regions  of  Continued  Growth.  —  In  dicotyledonous 
plants,  such  as  the  oak,  maple,  elm,  etc.  (B,  Fig.  47),  the 
regions  of  continued  growth  lie  at  the  apices  of  roots  and 
shoots,  in  the  cambium  zone  which  separates  the  bark  from 
the  wood,  and  in  certain  zones  of  cells  called  cork  cambium 
which  give  rise  to  the  cork  of  the  bark.      In  monocoty- 
ledonous  plants,  such  as  grasses  (A),  palms  (C),  etc.,  there 


Growth  and  Movement. 


in 


is  no  cambium  zone  similar  to  that  in  dicotyledonous  plants ; 
but  in  such  monocotyledonous  plants  as  the  palm  and  smi- 
lax  (C)  a  zone  of  cells  near  the  periphery  of  the  stem 
remains  in  a  dividing  condition  indefinitely,  and  thus  adds 
to  the  diameter  of  the  stem,  some  of  the  cells  of  the  periph- 


FlG.  47. 

Diagrams  showing  regions  of  continued  growth  in  dicotyledonous  and  monocoty- 
ledonous plants.  The  shaded  regions  are  capable  of  growth.  A,  a  Monocoty- 
ledon of  the  grass  type,  growth  taking  place  at  the  apices  of  the  stem  and  roots 
and  at  the  bases  of  the  younger  nodes ;  C,  a  Monocotyledon  of  the  palm  and 
lily  type,  the  apices  of  the  stem  and  roots  and  a  zone  (/)  near  the  periphery 
being  in  a  growing  state;  B, a  Dicotyledon,  growth  taking  place  at  the  apices  of 
the  stem  and  roots  and  at  the  cambium  ring  (z). 

eral  zone  undergoing  the  necessary  modifications  to  form 
new  vascular  bundles. 

In  such  monocotyledonous  stems  as  those  of  grasses  (A), 
increase  in  length  is  also  brought  about  by  the  division  of 
the  cells  at  the  base  of  each  node,  which  retain  the  power 


H2  Introduction  to  Botany. 

of  division  for  a  long  time.  It  is  a  matter  of  common 
observation  that  grass  stems  are  easily  pulled  apart  at  the 
nodes,  and  that  the  place  of  rupture  is  tender,  succulent, 
and  sweet ;  these  are  all  characteristics  of  regions  where 
cell  division  is  rapidly  going  on.  The  tender  bases  of  the 
nodes  of  grass  stems  are  strengthened  by  being  enwrapped 
by  the  bases  of  the  leaves. 

In  the  leaves  of  grasses,  and  in  all  leaves  which  become 
much  elongated,  or  which  spring  from  underground  bulbs, 
etc.,  division  of  the  cells  of  the  basal  portion  continues  for 
some  time ;  but  leaves  in  general  owe  their  growth  mainly 
to  the  enlargement  of  the  cells  which  constitute  them  in 
their  embryonic  condition  in  the  bud. 

In  some  plants,  the  elongation  produced  by  the  division 
of  the  cells  at  the  apex  is  continued  indefinitely  through  the 
growing  season,  as  illustrated  by  roses  and  morning-glory, 
while  in  others  the  elongation  of  the  shoot  soon  ceases  with 
the  formation  of  a  winter  bud,  as  shown  by  the  hickory  and 
horse-chestnut. 

86.  Phases  of  Growth.  — Observation  95  has  shown  us 
that  the  region  of  greatest  elongation  is  a  short  distance 
back  of  the  growing  apex;  this  is  the  region  where  the 
daughter  cells,  produced  by  cell  division,  are  increasing  in 
size.     Back  of  this  region,  elongation  has  ceased,  and  thick- 
ening of  the  cell  walls  and  changes  in  their  chemical  con- 
stitution and  in  the  condition  of  the  protoplasts  are  taking 
place.     We  might,    therefore,  speak    of   three   phases    of 
growth:  (i)  the  phase  of  cell  division;  (2)  the  phase  of 
cell  enlargement;  (3)  the  phase  of  cell  modification. 

87.  Conditions   Necessary  to   Growth.  —  The   conditions 
necessary  to  growth  are  essentially  the  same  as  those  requi- 
site to  the  germination  of  seeds,  which  is,  in  reality,  simply 
a  resumption  of  growth.     Water  must  be  at  hand  in  suffi- 


Growth  and  Movement.  113 

cient  quantity  to  render  the  cells  turgid ;  food  materials 
must  be  available  ;  there  must  be  a  certain  amount  of  exter- 
nal energy  in  the  form  of  heat ;  oxygen  must  be  present 
for  the  process  of  respiration,  resulting  in  the  setting  free 
of  internal  energy,  without  which  the  life  of  the  plant 
would  become  extinct;  finally,  there  must  be  an  inclination 
to  cell  division.  This  last  condition  is  itself  dependent,  to 


FIG.  48. 

A,  a  shoot  of  Virginia  creeper  growing  in  the  light.    B,  a  shoot  from  the  same  plant 
growing  in  partial  darkness. 

a  certain  degree,  on  the  others ;  but,  even  when  these  are 
favorable,  the  inclination  to  cell  division  does  not  always 
result,  as  we  see  in  the  cessation  of  growth  of  hickory 
shoots  in  the  height  of  the  growing  season,  and  in  the 
limited  growth  of  embryos  in  forming  seeds.  The  causes 
for  this  behavior  are  inherent  in  the  nature  of  the  cell,  and 
are  faithfully  transmitted  by  cell  division  from  generation 
to  generation. 


H4  Introduction  to  Botany. 

88.  Influence  of  Light  and  Gravity.  —  While  light  and 
gravity  are  not  necessary  to  the  immediate  processes   of 
growth,  they  do  influence  the  direction  and  character  of 
growth  of  the  plant  members,  as  we  have  already  seen. 
Light  has  much  to  do  with  the  size  and  form  of  the  mem- 
bers.    Compare,  for  instance,  a  shoot  of  Virginia  creeper 
which  has  grown  in  the  dark  with  one  which  has  grown 
fully  exposed  to  the  light  (Fig.  48).    We  see  in  such  a  case 
that  the  internodes  of  the  shoot  which  has  grown  in  the 
dark  are  much  longer  than  those  of  the  shoot  which  has 
developed  in  the  light,  while  its  leaves  are  considerably 
smaller  than  those  of  the  illuminated  shoot.     We  can  see 
the  usefulness  of   the   habit  of   greatly  elongating   inter- 
nodes  and  keeping  the  leaves  reduced  where  the  shoot  is 
in  much  darkened   places,  for  where   the   leaves  cannot 
have  access  to  the  light  they  require  materials  for  their 
production  which  they  cannot  replace  by  the  manufacture 
of  food  materials.     The  greater  elongation  of  internodes 
in  the  dark  brings  the  leaves  more  certainly  and  quickly 
into  illuminated  places. 

89.  Rings  of  Annual  Growth.  —  When  a  perennial  di- 
cotyledonous plant  resumes  growth  in  the  spring,  it  pro- 
duces more  branches  and  leaves  than  it  possessed  the  pre- 
vious year.     This  is  characteristic  of  branching  perennial 
plants.     In  consequence  of  the  increased  transpiring  sur- 
face and  weight  of  the  crown,  more  demands  are  made  on 
the  stems  and  roots,  for  they  must  be,  stronger,  and  they 
must  be  able  to  conduct  larger  supplies  of  water  to  the 
leaves.     Here  is  where  the   usefulness   of   the   cambium 
ring  is  shown ;  for  while  the  leaves  and  branches  are  being 
formed,  the  cells  of  the  cambium  ring  are   dividing   and 
adding  to  the  thickness  of  the  stems  and  roots.     The  tis- 
sues which  are  first  formed  by  the  cambium  are  of  a  nature 


Growth  and  Movement. 


to  meet  the  most  pressing  demand  at  the  time ;  namely,  for 
a  greater  water  supply  for  the  increased  transpiring  sur- 
face of  the  leaves.  Accordingly  we  find  that  a  great  many 
water  tubes  are  first  formed  (see  Fig.  49),  which  com- 
municate with  the  veins  of  the  leaves  and  with  the  water 
tubes  running  out  into  the 
newly  formed  rootlets. 

The  water  supply  having 
been  provided  for,  the  cam- 
bium cells  next  produce  wood 
fibers  in  much  greater  pro- 
portion. At  the  close  of*  the 
season  we  find  on  examining 
the  year's  growth  that  it  con- 
sists of  a  zone  of  tissues  (s) 
in  which  the  water  tubes  pre- 
dominate, followed  by  a  zone 
(/)  which  is  more  dense  and 
firm  because  the  water  tubes 
in  it  are  smaller  and  fewer, 
and  the  thick-walled  wood 
fibers  more  in  evidence.  A 
single  ring  of  annual  growth 
consists  then  of  a  zone  of 
early  growth  and  a  zone  of 

later  and  denser  growth,  each  zone  having  its  own  peculiar 
significance  in  the  economy  of  the  plant.  The  cambium 
ring  makes  annual  additions  to  the  bark  as  well  as  to  the 
wood,  but  in  much  less  quantity,  and  the  additions  are  not 
demarked  into  rings  of  growth. 

90.  Plants  without  Annual  Rings.  —  In  perennial  mono- 
cotyledonous  stems,  which  branch  but  little  or  not  at  all, 
the  crown  of  leaves  does  not  increase  materially  from  year 


FIG.  49. 

Constitution  of  a  ring  of  growth,  s  and 
u,  early  growth  ;  t,  late  growth.  The 
lowest  row  of  small  cells  in  s  belongs 
to  the  late  growth  of  the  previous 
year.  The  early  growth  here  con- 
sists chiefly  of  the  tracheal  tubes  and 
wood  parenchyma  and  the  late 
growth  chiefly  of  wood  fibers,  s  and 
t  constitute  an  annual  ring.  After 
HABERLANDT. 


FIG.  50. 


FIG.  51. 


FIG.  52. 


FIG.  53. 


Fig.  50.    Castor  bean  grown  under  equilateral  illumination. 

Fig.  51.  The  same  plant  after  some  hours  of  slow  revolution  on  a  universal 
axis. 

Fig.  52.  The  same  plant  after  a  few  hours  of  equilateral  illumination,  following 
the  condition  shown  in  Fig.  51. 

Fig.  53-  The  same  plant  after  a  few  hours  of  one-sided  illumination,  following 
the  condition  shown  in  Fig.  52. 


<^JJ^_^ 

**^K 


rv 


FIG.  54. 


FIG.  55. 


FIG.  56. 


FIG.  57. 


Fig.  54.  The  same  plant  after  a  few  hours  of  equilateral  illumination,  following 
the  condition  shown  in  Fig.  53. 

Fig.  55-    Another  castor  bean  plant  grown  under  equilateral  illumination. 

Fig.  56.  The  same  plant  as  shown  in  Fig.  55  after  being  inverted  for  a  few  hours 
under  equilateral  illumination. 

Fig.  57.  The  same  plant  after  being  set  erect  for  a  few  hours  under  equilateral 
illumination,  following  the  condition  shown  in  Fig.  56. 


n8  Introduction  to  Botany. 

to  year,  and  new  additions  to  the  water-conducting  ele- 
ments and  to  the  strengthening  elements  are  not  so  neces- 
sary as  in  the  case  of  branching  dicotyledonous  stems. 
Accordingly,  we  find  that  most  monocotyledonous  stems 
increase  but  little  in  thickness,  and  give  no  evidence  of 
rings  of  annual  growth,  since  the  bundles  are  scattered, 
and  there  is  no  true  cambium  ring.  The  grass  stem,  which 
represents  in  its  general  structure  a  vast  number  of  endoge- 
nous stems,  is  a  marvelous  example  of  architectural  achieve- 
ment, for  its  height  is  often  five  hundred  times  its 
diameter.  If  Washington  Monument  were  built  in  like 
proportions  its  base  would  cover  an  area  of  less  than  one 
square  foot.  Stems  of  this  sort,  which  increase  but  little 
in  diameter,  show  us  how  perfectly  plants  are  constructed 
from  the  purely  mechanical  standpoint. 

91.  Sensibility  of  the  Protoplasts.  —  One  of  the  most  re- 
markable things  about  the  live  part  of  the  cell,  namely,  the 
protoplast,  is  its  sensibility  to  its  surroundings,  and  its 
capacity  to  respond  in  certain  definite  ways  to  varying 
external  conditions.  The  polarity  of  plants,  as  we  see  it 
exhibited  in  root  and  shoot,  is  an  expression  of  this  sensi- 
bility, since  the  protoplasts  of  the  cells  of  the  root  use 
gravity  to  guide  their  part  of  the  plant  body  downward, 
while  those  of  the  shoot  find  the  upward  direction  by  the 
same  force.  The  stem  of  the  trumpet  creeper  finds  its 
way  to  a  support  through  the  perception  of  light,  while  the 
leaves  are  directed  away  from  the  support  and  toward  the 
light  by  the  same  means. 

If,  by  any  accident,  a  plant  becomes  overturned  or  bent 
out  of  its  normal  position,  the  protoplasts  perceive  the 
altered  relation  to  light  and  gravity,  and  cause  the  growing 
members  to  shift  their  positions  into  proper  relations  to 
these  forces.  Figure  50  is  a  photograph  of  a  young  castor 


Growth  and  Movement.  119 

bean  plant  which  has  been  grown  in  a  pot,  and  kept 
equally  illuminated  on  all  sides.  Figure  5 1  shows  the  same 
plant  after  revolving  for  eighteen  hours  on  both  horizontal 
and  vertical  axes  at  the  same  time,  so  that  both  light  and 
gravity  as  a  guide  were  useless  to  it.  Its  protoplasts  ap- 
pear to  have  perceived  its  abnormal  condition,  and  have 
changed  the  position  of  the  leaves ;  having  no  guide,  how- 
ever, only  fruitless  curvatures  have  resulted. 

Figure  52  represents  the  same  plant  after  standing  eigh- 
teen hours  in  a  normal  position  under  equilateral  illumina- 
tion ;  the  protoplasts  have  found  their  direction  again,  and 
have  placed  the  leaves  more  nearly  in  their  wonted  position. 
Figure  53  represents  this  plant  after  being  next  illuminated 
on  one  side  only  for  twenty-four  hours ;  the  protoplasts  of 
both  stem  and  leaves  have  attempted  to  bring  the  leaves 
into  position  for  receiving  as  much  as  possible  of  the  inci- 
dent light.  Figure  54  shows  the  same  plant  again  after 
being  equally  illuminated  on  all  sides  for  about  twenty- 
four  hours ;  since  there  was  the  same  degree  of  light 
intensity  on  all  sides,  gravity  has  evidently  been  em- 
ployed to  bring  the  parts  back  from  their  one-sided 
position. 

Figure  55  is  a  photograph  of  another  plant  which  has 
grown  in  a  pot  under  normal  conditions.  Figure  56  repre- 
sents the  same  plant  after  standing  inverted  for  about 
eighteen  hours  while  kept  equally  illuminated  on  all  sides 
by  rotation  on  a  vertical  axis ;  a  very  successful  attempt 
has  been  made  to  bring  the  leaves  and  stem  back  to  their 
normal  relations  to  light  and  gravity.  (To  see  this  to  best 
advantage  hold  the  book  upside  down.)  Figure  57  shows 
the  same  plant  again  after  standing  erect  under  equilateral 
illumination,  the  stem  and  younger  leaves  having  assumed 
approximately  their  original  positions. 


I2O  Introduction  to  Botany. 

92.  Greater  Sensibility  of  Growing  Members.  —  In  com- 
paring  these   photographs,   it    is    seen  that   the   younger 
portions  of  the  stem    and  the   younger   leaves  are  more 
responsive  to  the  reversed  position  or  to  unilateral  forces. 
It  appears  that,  in  the  older  members,  the  protoplasts  may 
be  less  sensitive  to  external  forces,  and  that  it  is  a  more 
difficult  matter  for  the  older  and  somewhat  rigid  parts  to 
change  their  positions. 

93.  Cause  of  Movements.  —  The   movements  which  we 
have  just  observed  are  due  to  a  more  rapid  growth  on  one 
side  of  the  leaves  and  stem  than  on  the  other.     When  the 
plant  is  inverted,  the  cells  on  the  lower  side  of  the  petioles 
and  leaf  blades  and  on  the  lower  side  of  the  stems  increase 
in  size  more  rapidly  than  those  of  the  upper  side,  and  there 
is  accordingly  a  general  bending  of  these  parts  upward. 
When  the  plant  is  illuminated  on  one  side  more  than  on 
another,  growth  is  most  rapid    on   the  side  remote  from 
the  source  of  greatest  illumination.     When  a  plant  which 
has  made  a  one-sided  growth  under  such  circumstances  is 
again  placed  so  that  it  is  equally  illuminated  on  all  sides, 
its  parts  draw  back  toward  their  normal  position,  provided 
they  are  not  too  old  for  growth  ;  but  in  order  that  this  may 
occur,  growth  must  take  place  on  one  side  more  than  on 
another,  although   all  sides  are   now  equally  illuminated. 
It  appears  that  in  such  cases  gravity  is  used  as  a  guide, 
and  that  the  protoplasts  persist  in  causing  unilateral  growth 
until  the  stems  and  leaves  stand  in  their  normal  positions. 
The  experiment  illustrated  in  Fig.  51  is  very  instructive, 
for  it  teaches  that  when  the  directive  influence  of  all  ex- 
terior forces  is  removed  the  protoplasts  are  no  longer  able 
to  determine  a  definite  position  for  the  stems  and  leaves. 

94.  Heliotropism.  —  As  we   have    seen  in  the  study  of 
leaves,  the  interception  of  sunlight  is  of  vital  importance 


Growth  and  Movement. 


121 


to     plants,     and 
therefore     light 
is  the  most  fea- 
sible    guide    in 
determining  the 
position  of  leaves 
and  leaf-bearing 
branches.  Since, 
however,      the 
source  of  great- 
est   illumination 
hourly    changes 
as   the   sun    ad- 
vances from  east 
to  west,  it  is  plain 
that  if  the  posi- 
tion of  leaves  is 
fixed  once  for  all, 
the  best  possible 
light  relation  is 
not     attained. 
The  behavior  of 
a  rapidly  grow- 
ing   sunflower 
shows      how 
plants  may  take 
account    of    the 
shifting  light. 
The  three  photo- 
graphs of  Fig.  58 
show   the    same 
plant   as    it   ap- 
peared    in     the 


122  Introduction  to   Botany. 

morning,  at  noon,  and  in  the  late  afternoon  of  a  single 
day.  It  can  be  seen,  by  comparing  the  same  leaves 
in  the  different  photographs,  that  they  were  incessantly 
striving  to  intercept  as  much  light  as  possible  by  keeping 
their  broad  surfaces  at  right  angles  to  the  changing  direc- 
tion of  greatest  illumination.  Such  movements,  and  any 
others  caused  by  light,  are  designated  as  heliotropic,  and 
the  state  or  condition  of  plants  which  makes  heliotropic 
movements  possible  is  termed  heliotropism.  The  student 
may  observe  many  other  plants  which  exhibit  high  degrees 
of  motility  of  this  kind. 

95.  Influence  of  Various  Forces.  —  The  movements   ex- 
hibited by  plant  members,  for  which  light  and  gravity  are 
the  guiding  forces,  are  of  the  most  vital  significance  to  the 
plant;    but  there  are   movements  which  are  directed  by 
other   means.      Observation  99  has  taught  us  that   roots 
may  disregard  gravity  and  turn  in  the  direction  of  moist 
areas;   and  we  saw  by  Observation    103  that  by  contact 
with  an  object,  tendrils  of  some  plants  may  be  made  to 
grow  on  one  side  more  than  on  another  so  that  they  twine 
about  the  object  if  it  is  of  suitable  size  and  shape.     There 
are   other   movements    due  to  unequal   growth,  exhibited 
chiefly  by  the  parts  of  flowers,  which  are  induced  by  vary- 
ing degrees  of  light  and  heat.    The  flowers  of  Tulip,  Crocus, 
Colchicum,  etc.,  will  open  in  a  few  minutes  if  the  tempera- 
ture is  raised  to  a  marked  degree,  and  at  a  constant  tem- 
perature they  will  open  in  the  light  and  close  in  the  dark. 
It  is  a  matter  of  common  observation  that  the  dandelion 
behaves  in  this  way. 

96.  Motor  Organs.  —  Old  plant  members  which  exhibit 
movements  are  usually  provided  with  special  structures  for 
that  purpose.     A  description  of  the  behavior  of  the  leaves 
of  scarlet  runner,  and  of  their  motor  organs,  will  serve  to 


Growth  and  Movement. 


123 


illustrate  this.  Figure  59  represents  a  leaf  in  its  night  posi- 
tion; at  a,  b,  and  c  (Fig.  60)  are  the  motor  organs.  The  posi- 
tions of  the  motor  organs  of  the  leaflets  are  shown  for  the 
nighttime  at  B,  and  for  the  daytime  at  A.  Cross  sections 
of  a  petiole  and  of  a  motor  organ  are  shown  at  C  and  D. 

It  is  seen  that 
while  the  petiole 
is  made  rigid  by 
the  disposition  of 
its  vascular  bun- 
dles in  a  circle 
outside  the  cen- 
ter, as  seen  at  C, 
and  by  the  wing- 
like  outgrowths 
containing  each 
a  vascular  bundle 
g,  the  vascular 
bundles  in  the 
motor  organ  are 

all  thrown  to  the  center;  and  surrounding  them  is  a  relatively 
broad  zone  of  thin-walled  parenchymatous  tissue  which  is 
capable  of  undergoing  great  variation  in  the  turgidity  of 
its  cells.  In  the  nighttime  the  upper  portion  of  the  paren- 
chymatous tissue  of  the  motor  organ  of  the  petiole  becomes 
less  turgid  than  the  under  portion,  and  the  leaf  as  a  whole 
rises  in  consequence ;  but  at  the  same  time  the  motor  or- 
gans of  the  individual  leaflets  become  less  turgid  on  the 
under  side,  and  the  leaflets  are  made  to  droop.  In  the 
daytime  the  motor  organs  of  the  leaflets  become  less  turgid 
on  their  upper  sides,  and  the  leaflets  rise  in  consequence, 
while  the  motor  organ  of  the  petiole  becomes  less  turgid  on 
its  under  side  and  the  leaf  as  a  whole  drops  to  a  lower  plane. 


FIG.  59. 


Leaf  of  Scarlet  Runner  in  its  night  position. 
After  SACHS. 


I24 


Introduction  to  Botany. 


Such  movements  are  in  harmony  with  the  functions  of 
the  leaf,  for  the  leaflets  are  spread  out  to  receive  the 
light  necessary  to  photosynthesis  in  the  daytime,  and  are 
folded  together  in  the  nighttime  so  that  they  are  less  apt 
to  receive  injury  from  too  great  radiation  of  heat  or  from 
the  beating  of  storms.  The  variations  in  the  turgidity  of 
the  motor  organs  are  induced  and  regulated  by  the  proto- 
plasts, which  are  influenced  in  their  action  by  variations  in 


FIG.  60. 


Motor  organs  (a,  b,  and  c)  of  Scarlet  Runner  in  their  day  position  at  A,  and  in  their 
night  position  at  B.  C,  a  cross  section  of  a  petiole,  and  D  of  a  motor  organ. 
After  SACHS. 

light  intensity.  Periodic  movements  induced  by  alterna- 
tions of  day  and  night  may  be  observed  in  the  oxalises 
(commonly  represented  by  the  violet  and  yellow  wood 
sorrel)  and  in  many  members  of  the  pulse  family. 

97.  The  Sensitive  Plant.  —  Movements  of  the  leaves  of 
some  plants  may  be  induced  by  contact  with  a  solid  body, 
by  shaking  the  entire  plant,  by  intense  illumination,  or  by 
chemical  stimulus,  etc.  The  sensitive  plant,  Mimosa pudica, 


Growth  and  Movement. 


125 


affords  a  most  no- 
table example. 
Figure  61  shows 
photographs  of  a 
seedling  of  this 
plant  under  dif- 
ferent conditions : 
A  represents  the 
plant  in  diffuse 
light,  with  its  leaf- 
lets spread  out  to 
catch  the  light ; 
B  shows  the  leaf- 
lets somewhat 
folded  together  as 
the  result  of  a 
short  exposure  to 
direct  sunlight ; 
in  this  position 
the  leaflets  stand 
more  nearly  paral- 
lel with  the  inci- 
dent light ;  C  ex- 
hibits the  plant 
directly  after 
being  shaken  by 
a  strong  wind. 

Figure  62  rep- 
resents a  leaf  of 
a  mature  sensitive 
plant  in  its  open 
position  at  A,  and 
in  its  closed  posi- 


126  Introduction  to   Botany. 

tion  at  B,  after  being  touched  or  shaken.  If  one  of  the 
leaflets  of  the  upper  pair  be  lightly  touched,  it  will  rise, 
and  its  mate  will  quickly  rise  with  it ;  the  next  pair  of  leaf- 
lets soon  fold  together  in  a  similar  manner,  and  so  on  with 
succeeding  pairs,  until  all  of  the  leaflets  of  a  secondary 
petiole  have  responded  to  the  stimulus  received  by  the 
upper  leaflet ;  indeed,  all  of  the  leaflets  on  all  of  the  sec- 
ondary petioles  may  respond  to  a  stimulus  received  by  a 

single  leaflet. 

There  is,  therefore,  a 
transmission  of  a  stimulus 
from  one  part  of  the  plant 
body  to  another,  such  as 
takes  place  in  animals  by 

means  of  the  nerves ;  but 
FIG.  62.  -1,1 

in  plants  there  are  no  struc- 

A,  mature  leaf  of  the  Sensitive  Plant  fully     tures  Corresponding  to  the 
expanded;   B,  the  same  after  stimula- 

tion.   After  DUCHARTRE.  nerves  of  animals,  and  the 

exact  manner  of  the  trans- 
mission of  a  stimulus  is  not  positively  known.  It  is  known, 
however,  that  in  the  case  of  the  sensitive  plant  the  trans- 
mission can  take  place  through  portions  of  the  petiole 
which  have  been  killed.  Whatever  the  method  of  trans- 
mission may  be,  the  reception  of  the  stimulus  is  by  the 
living  protoplast,  and  the  reactions  which  follow  are 
caused  by  it.  The  benefits  to  be  derived  from  actions  of 
this  kind  are  obvious :  in  rain  or  hail  storms,  or  in  strong 
winds,  the  leaflets  fold  together,  and  become  much  less 
liable  to  injury.  Mimosa  pudica  affords  an  example  of 
extreme  sensitiveness.  There  are  many  other  sensitive 
plants  belonging  to  the  same  family  which  are  of  common 
occurrence;  Cassia  chamcecrista  and  nictitans  and  Schrankia 
uncinata  are  good  examples. 


Growth  and  Movement. 


127 


FIG.  63. 

Dion&a  muscipula.  Some  of  the  leaves 
stand  open,  and  others  are  closed  after 
stimulation  by  contact  with  insects. 
After  KERNER. 


98.  Action  of  Venus's  Flytrap.  —  In  Venus's  flytrap,  Dio- 
ncea  muscipula  (Fig.  63),  and  in  sundew,  Drosera  rotnndi- 
folia  (Fig.  65),  we  find  still 
more  wonderful  sensibility 
and  transmissions  of  stimuli. 
The  two  halves  of  a  leaf  of 
Venus's  flytrap  are  capable 
of  closing  together  as  if 
they  were  hinged  along  the 
median  line  (see  Fig.  64). 
The  margin  of  each  half  is 
provided  with  from  12  to 
20  teeth,  and  at  the  center 
of  each  half  there  are  three 
hairs  and  numerous  rose- 
colored  glands.  The  three  central  hairs  are  specially  con- 
cerned with  the  reception  of  stimuli,  for  although  the  leaves 
are  impassive  to  contact  at 
other  places,  when  any  of 
the  hairs  have  been  touched, 
the  two  halves  close  up 
rapidly  until  the  marginal 
teeth  are  interlocked.  The 
hairs  are  sensitive  in  this 
way  to  solid  bodies,  but 
not  to  the  wind  and  rain. 
When  an  insect  has  been 
caught  by  the  closing  leaves, 
the  glands  on  each  half  pour 


FIG.  64. 

M,  leaf  of  Dioncea  muscipula;  N,  cross 


section  of  the  trap  part  of  the  leaf  in  its 
closed  position.    After  KERNER. 


out    a    digestive    ferment, 

and  the  insect  is  held  until 

it  is  digested  and  absorbed,  this  process  requiring  from  one 

to  two  weeks,  according  to  the  size  of  the  insect.     Then 


128 


Introduction  to  Botany. 


the  leaf  slowly  opens  and  is  ready  for  another  victim. 
However,  if  the  insect  digested  is  large,  the  leaf  may  find 
itself  unable  to  perform  its  trap  function  a  second  time. 

99.  Behavior  of  Sundew.  —  The  leaves  of  Drosera,  or 
sundew,  are  orbicular,  and  bear  on  their  upper  surface 
glandular  structures  resembling  tentacles  (see  Fig.  65),  the 
tips  of  which  exude  a  clear  viscous  fluid.  When  an  insect 
alights  on  the  leaf  it  becomes  entangled  in  the  viscid  ex- 
cretion, its  struggles  excite  the  glands  to  greater  activity, 
and  more  and  more  fluid  is  exuded ;  at  the  same  time  the 

tentacles  bend 
down  over  the 
insect,  and  ren- 
der escape  more 
difficult.  The 
viscous  fluid  has 
the  nature  of  a 
digestive  fer- 
ment, and  by  it 
the  insect  is  ren- 
dered soluble, 
andinthiscondi- 
ition  is  absorbed 
by  the  leaf.  The 

glands  appear  insensible  to  falling  raindrops,  but  Darwin 
found  that  motion  was  induced  when  he  placed  on  a  ten- 
tacle a  bit  of  hair  weighing  only  y^^-  of  a  grain.  He 
found  the  tentacle  to  be  quite  sensitive  also  to  very  dilute 
solutions  of  nitrogenous  salts ;  they  bent  downward  com- 
pletely when  the  leaves  were  immersed  in  a  solution  of 
ammonium  carbonate  so  dilute  that  each  gland  could 
absorb  no  more  than  37  oFo  wo  of  a  grain.  This  experi- 
ment serves  at  least  to  show  that  the  sensibility  of  plants 


Leaves  of  Drosera  rotundifolia,  a,  after  stimulation  by 
contact  with  an  insect,  and  b,  with  all  of  the  tentacles 
expanded.  After  KERNER. 


Growth  and   Movement. 


129 


may  approximate  or  even  surpass  in  some  respects  that  of 
animals. 

100.   Spontaneous  Movements.  —  The  movements  of  plants 
which  have  thus  far  been  mentioned  are  evidently  induced 


FIG.  66. 


Two  photographs  of  the  same  seedling  Morning  Glory.  A,  after  growing  under 
usual  conditions,  the  light  stronger  from  the  right ;  B,  after  revolving  on  a  uni- 
versal axis  immediately  following  the  condition  shown  in  A. 

or  guided  by  some  external  force,  although  in  all  cases  the 
protoplast  is  the  immediate  cause  of  the  movement.  There 
is,  however,  another  class  of  movements  which  seem  to 
require  no  external  stimulus  other  than  those  conditions 
which  are  necessary  to  the  healthy  existence  of  the  plant. 


130  Introduction  to  Botany. 

The  growing  apices  of  roots  and  shoots  are  almost  con- 
stantly in  motion,  describing  more  or  less  irregular  ellipses. 
Such  movements  are  usually  so  slight  as  to  be  inappreci- 
able without  the  use  of  instruments  for  measuring  move- 
ments through  minute  distances. 

101.  Twining  Plants.  —  The  rotating  movements  of  the 
apices  of  twining  plants  differ  from  spontaneous  move- 
ments, not  only  in  degree,  but  also  in  kind,  for  they  depend 
on  gravity  for  their  accomplishment.     This  is  shown  by 
Fig.  66,  which  illustrates  a  morning-glory  that  has  grown 
up  a  support  under  normal  conditions,  and  the  same  plant 
after  it  has  been  revolving  on  a  horizontal  axis  and  on  a 
vertical  axis  at  the  same  time  for  a  period  of  about  eight 
hours.     In  the  latter  instance  the  plant  not  only  ceased  to 
twine,  but  actually  untwined  as  far  back  as  growth  in 
length  was  still  taking  place.     The  revolution  of  a  plant 
on  both  horizontal  and  vertical  axes  at  the  same  time  elimi- 
nates the  directive  influence  of  all  exterior  forces ;  but  that 
it  is  the  elimination  of  the  influence  of  gravity,  and  not 
that  of  light,  which  has  caused  the  plant  to  untwine  is 
shown  by  the  fact  that  under  otherwise  normal  conditions 
it  continues  to  twine  in  darkness. 

102.  Method  of   Twining.  —  Most  twining  plants  twine 
contrary  to  the  movement  of  the  hands  of  a  watch,  that 
is,  the  coil  facing  the  observer  passes  from  the  left  below 
to  the  right  above.     Some  plants,  however,  twine  in  the 
opposite  direction,  and  some  twine  indifferently  in  both 
directions.     The  seedling  twining  plant  does  not  show  a 
tendency  to  twine  for  the  first  one  or  two  internodes,  but 
after  that  the  apical  portion  bends  over  by  its  own  weight 
to  a  position  more  or  less  horizontal,  and  then,  if  it  is  a 
left  to  right  twiner  and  the  apex  is  bent  toward  the  north, 
for  instance,  the  east  side  of  the  stem  begins  to  grow  faster 


Growth  and   Movement.  131 

than  the  others,  causing  the  apex  to  bend  toward  the  west ; 
then  the  region  of  greatest  growth  is  on  the  north  side, 
resulting  in  the  bending  of  the  apex  toward  the  south,  and 
so  on. 

By  movements  of  this  sort  the  plant  is  able  to  feel  about 
in  space  for  some  support,  and  having  found  it  to  twine 
about  it.  If  growth  ceased  in  the  coils  as  fast  as  they 
were  made,  the  plant  would  rise  upward  little  or  not  at  all, 
and  the  successive  coils  of  the  stem  would  lie  near  together 
or  over  each  other.  This,  however,  is  prevented  by  the 
continued  growth  of  the  stem  for  some  time  after  the  coils 
have  been  laid  down,  the  growth  then  being  most  rapid  on 
the  under  side  of  the  coils,  causing  them  to  rise  upward 
and  become  spread  apart  in  the  form  of  a  spiral ;  at  the 
same  time  the  stem  is  brought  into  closer  contact  with  the 
support. 

The  benefit  of  the  twining  habit  is  easy  to  see,  for  those 
plants  which  possess  it  are  able  to  raise  their  leaves  to  the 
sunlight  with  a  very  small  expenditure  of  energy  and 
materials  for  the  construction  of  strong  stems. 

103.  Source  of  Internal  Energy.  —  How  the  living  proto- 
plast is  able  to  carry  out  the  processes  of  growth  and 
movement  is  a  mystery.  We  know  in  regard  to  it,  how- 
ever, that  the  protoplast  ceases  its  activity  and  dies  unless 
a  certain  amount  of  internal  energy  is  available,  resulting 
from  the  oxidation  of  the  substance  of  the  protoplast  and 
of  reserve  materials ;  no  amount  and  no  form  of  external 
energy  can  take  the  place  of  this.  The  more  rapidly 
growth  and  movement  take  place  the  greater  the  amount 
of  materials  consumed.  This  oxidation  of  the  substance 
of  the  protoplast  and  of  the  reserve  materials  is  the  essen- 
tial process  of  respiration,  in  plants  as  in  animals.  The 
active,  or  kinetic,  energy  resulting  from  respiration  is  in 


132  Introduction  to  Botany. 

part  immediately  employed  in  the  work  of  the  protoplasts, 
and  in  part  lost  to  the  plant  in  the  form  of  heat  by  radia- 
tion and  conduction,  and  in  the  evaporation  of  water  from 
the  tissues.  The  internal  energy  which  appears  during 
respiration  was  obtained  for  the  most  part  from  the  sun 
during  the  process  of  photosynthesis,  and  in  part  from  the 
salts  from  the  soil,  and  stored  within  the  plant  in  the  form 
of  potential  energy  in  starch,  sugar,  proteids,  etc. ;  and  as 
active  energy  from  the  sun  was  required  to  form  these  sub- 
stances, so  now  it  is  evolved  when  they  are  broken  down 
by  oxidation.  If  we  are  to  understand  the  essential  thing 
about  photosynthesis,  we  must  perceive  it  as  a  process  of 
storing  the  sun's  energy  in  such  a  form  as  to  make  it 
available  to  plants  by  night  as  well  as  by  day,  and  through- 
out all  seasons  of  the  year. 

104.  Oxidation  a  Vital  Process.  —  The  process  of  respira- 
tion is  not  a  passive  oxidation,  but  is  induced,  and  to  a 
certain   extent   regulated,    by  the   living    protoplast.      In 
plants,  however,  the  regulation  of  oxidation  is  not  by  any 
means  so  exact  as  in  warm-blooded  animals,  whose  tem- 
perature is  allowed  to  fluctuate  only  within  very  narrow 
limits,  while  the  temperature  of  plants  under  normal  con- 
ditions seldom  differs  much  from  that  of  the  surrounding 
atmosphere. 

105.  Annuals,  Biennials,  and  Perennials.  —  A  large  class 
of  plants  bears  seeds  the  first  year,  and  in  so  doing  these 
plants  send  into  the  seed  so  much  of  their  stored  energy 
that  they  are  unable  to  survive  the  winter,  or  in  some  cases 
even  to  continue  to  the  end  of  the  summer.     Such  pi?  its 
are  known  as  annuals.     Many  other  plants  store  up  the 
energy   accumulated   by    photosynthesis   in    underground 
parts,  such  as  tubers,  bulbs,  etc.,  and  having  survived  the 
winter  produce  their  seeds  and  die  at  the  end  of  the  second 


Growth  and   Movement.  133 

season;  these  are  known  as  biennials.  Still  other  plants 
keep  in  reserve  sufficient  energy  to  maintain  their  indi- 
vidual existence  year  after  year ;  these  are  termed  peren- 
nials. The  production  of  seeds  is  in  the  interest  of  the 
species,  but  not  of  the  individual,  upon  which  it  is  a  severe 
tax,  and  only  those  plants  can  survive  it  that  can  retain 
within  their  own  bodies  a  good  amount  of  reserve  energy. 
Some  perennials  further  protect  the  individual  life  by 
alternate  years  of  seed-bearing  and  sterility. 

106.  Length  of  Life.  —  Some  perennials  attain  an  enor- 
mous age.     A  Taxus  tree  in  Kent  is  considered  to  be  3000 
years  old,  and  an  Adansonia  in  the  Cape  Verde  Islands 
and  a  Taxodium  in  Mexico  appear  to  have  lived  for  6000 
years.     It  must  be  remembered,  however,  about  plants  of 
great  age,  that  those  of  their  tissues  which  are  actually 
alive  are  of  comparatively  recent  production ;    the  older 
tissues  are  gradually  dying,  while  new  tissues  are  being 
formed.     Since  perennial  plants  are  annually  rejuvenated 
by  the  formation  of  new  tissues,  it  would  seem  that  they 
might  live  indefinitely;    but  changes  in  the  character  of 
the  soil,  the  ravages  of  storms  and  parasites,  and  com- 
petition with  other  individuals  sooner  or  later  bring  their 
life  to  an  end. 

107.  Nature  of  Growth.  —  If  we  were  to  attempt  a  formal 
definition  of  growth,  we  might  say  that  it  is  any  permanent 
change  in  the  form  and  size  and  internal  structure  which  is 
brought  about  by  the  action  of  the  protoplasts.     Growth 
does  not  always  involve  an  increase  in  weight,  for  germi- 
n  ting  seeds  are  actually  decreasing  in  weight  by  the  oxida- 
tk  i  of  their  reserve  materials ;  neither  could  temporary 
incr  ^ase  in  size  by  the  imbibition  of  water  be  classed  as 
growth. 


CHAPTER  VII. 
MODIFIED  PARTS. 

PROVIDING   MATERIALS. 

Material  for  the  study  of  the  morphology  of  spines  can  be  procured 
at  any  time  of  the  year,  but  branches  for  the  study  of  the  spines  of  bar- 
berry should  be  gathered  while' in  leaf,  and  either  pressed  or  preserved 
in  2  %  formalin.  The  wild  smilax,  whose  tendrils  are  excellent  material 
for  morphological  study,  should  be  gathered  during  the  summer  and 
preserved  as  suggested  for  barberry.  The  greenhouse  smilax  can,  of 
course,  be  obtained  at  any  time  of  the  year  from  greenhouses ;  and 
nothing  could  be  better  than  this  for  testing  the  ability  of  students  in 
seeking  out  morphological  evidence.  Utricularia  should  be  gathered 
from  ponds  and  shallow  lakes  during  the  summer  and  preserved  in  2  % 
formalin. 

OBSERVATIONS. 

Most  plant  members  are  either  roots,  stems,  or  leaves, 
and  for  the  sake  of  classification  these  may  be  taken  as  the 
morphological  elements,  although  some  structures  have  a 
different  origin.  To  determine  the  origin  of  a  modified 
structure,  that  is,  whether  it  is  a  root,  stem,  leaf,  etc., 
evidence  along  the  following  lines  should  be  sought : 
(i)  arrangement;  (2)  relation  to  other  structures;  (3)  tran- 
sitional forms;  (4)  construction.  Thus,  under  i,  is  there  a 
definite  arrangement,  a  fixed  angular  divergence  ?  Under  2, 
does  the  structure  have  a  definite  and  constant  relation  to 
a  leaf  or  bud?  Under  3,  can  forms  be  found  which  are 
less  and  less  like  the  modified  form  in  question,  and  more 
and  more  like  a  typical  morphological  element  ?  Under  4, 

134 


Modified  Parts.  135 

is  it  composed  of  bark,  wood,  and  pith,  or  of  one  or  two  of 
these  ?  The  evidence  under  4  is  not  entirely  reliable,  since 
the  modification  of  a  structure  may  involve  the  suppression 
of  some  of  its  tissues.  Before  proceeding  with  the  study 
of  modified  structures,  write  out  the  characteristics  under 
I,  2,  and  3,  of  a  typical  root,  stem,  and  leaf  (see  Discussion 
no).  It  must  be  remembered  that  form  and  physiological 
function  do  not  furnish  reliable  evidence  as  to  the  mor- 
phology of  a  modified  structure ;  this  should  be  tested  as 
you  proceed  with  the  studies  outlined  in  this  chapter. 

109.  Make  a  drawing  of  a  spine  of  wild  plum,  showing 
its  form,  size,  mode  of  attachment  to  the  stem,  and  position 
on  the  stem  with  reference  to  nodes  and  internodes.  Show 
its  relation  to  buds,  branches,  leaves,  or  leaf  scars.  To 
show  the  attachment  to  the  stem,  make  a  median  longitu- 
dinal section  through  the  spine  and  the  branch  which  bears 
it,  and  draw  the  cut  surface. 

no.  Give  the  morphology  of  the  spine,  that  is,  state 
what  one  of  the  morphological  elements  has  been  modified 
to  form  this  structure,  and  give  in  your  notes  all  of  the 
evidence  for  your  decision,  as  suggested  under  I,  2,  3,  etc., 
of  the  introductory  note.  Refer  to  the  details  of  your 
drawings  by  letters  or  numbers  for  each  point  of  evidence. 
Determine  the  probable  function  of  the  spine,  and  give 
reasons  in  full  for  your  conclusion.  It  is  not  possible  to 
demonstrate  a  useful  function  for  every  structure.  Some 
modified  structures  seem  to  have  arisen  either  from  lack  of 
nutrition  or  from  abundant  nutrition,  and  in  either  case 
they  may,  or  may  not,  be  useful.  The  student  should  not 
attribute  a  function  to  a  structure  without  good  evidence. 

in.  In  a  similar  manner,  work  out  the  morphology  of 
the  spines  of  the  honey  locust,  black  locust,  prickly  ash, 
and  osage  orange. 


136  Introduction  to  Botany. 

112.  Determine,  as  above,  the  morphology  of  the  ten- 
drils of  the  wild  smilax  and  Virginia  creeper,  or  grape. 

113.  Work  out  the  evidence  for  the  morphology  of  the 
spines  of  barberry. 

114.  Determine  the  morphology  of  all  structures  which 
are  borne  on  the  stems  of  Asparagus  medioloides  (green- 
house smilax). 

115.  What  is  the  morphology  of  the  prickles  of   rose 
and  gooseberry  ? 

116.  Determine  the  morphology  of  an  onion  bulb. 

117.  What  is  the    morphology  of    the   tuber   of    Irish 
potato,  and  of  the  structures  borne  on  it  ? 

1 1 8.  Determine   the   morphology   of    the   bladders    of 
Utricularia  or  bladderwort. 

DISCUSSION. 

108.  Diversity  of  Plant  Forms.  —  The  great  diversity  of 
plant   forms,  as  we  now  find   them,  has    doubtless   been 
evolved  from  comparatively  few  and  simple   forms.     No 
two  plants  are  entirely  alike,  and  probably  no  structure  is 
exactly  like  any  other  of  the  same   kind.     Compare   the 
leaves  on  a  plant  and  note  how  dissimilar  they  are  in  form, 
size,  and  outline,  and  what  endless  varieties  of  leaves  are 
on  the  different  kinds  of  plants.     Such  facts  as  these  are 
an  expression  of  the  extreme  plasticity  of  the  plant  body, 
which  seems  to  respond  to  external  conditions  and  forces, 
and  to  internal  tendencies,  like  clay  to  the  hands  of  the 
potter ;  yet  we  must  remember  that  the  infinite  variety  of 
forms  which  we  now  see  has  been  evolving  through  the 
untold  years  since  life  began  upon  the  earth. 

109.  Morphological    Elements.  —  After   plants   had    ad- 
vanced in  their  evolution  from  the  un differentiated  body 
known  as  the  thallus  (see  pages  257  to  285)  to  the  forms 


Modified  Parts. 


137 


having  roots,  stems,  and  leaves,  they  seem  to  have  found  in 
these  a  sufficient  number  and  kind  of  members  for  the  suc- 
cessful nutrition  of  the  individual  (we  may  consider  struc- 
tures of  the  nature  of  hairs  and  prickles  as  outgrowths  of 
roots,  stems,  and  leaves  without  grouping  them  as  distinct 
morphological  elements).  We  find  very  few  plant  members 
which  may  not  be  classified  certainly  as  either  roots,  stems, 
or  leaves,  and  for  this  reason  we 
may  speak  of  these  members  as  the 
morphological  elements,  without  im- 
plying that  no  other  members  may 
sometimes  occur.  Thus,  when  for 
any  reason  plants  have  need  of  new 
structures,  it  is  their  habit  to  modify 
one  of  these  elements  to  meet  the 
new  demand.  When  Solanum  jas- 
minoides,  for  instance  (Fig.  67),  was 
acquiring  the  climbing  habit  it  put 
into  its  petioles  sensibility  to  contact, 
and  power  to  respond  in  such  a  way 
as  to  twine  about  the  object  with 
which  it  came  in  contact.  Or,  when 
the  turnip  began  to  store  up  food 
for  use  in  the  succeeding  year,  in- 
stead of  producing  a  new  member 
as  a  storehouse  for  reserve  food,  its  tap  root  was  incited 
to  increase  in  size  sufficiently  for  this  purpose.  So,  too, 
when  buds  were  to  be  protected,  internodes  were  kept 
short,  and  the  leaves  were  so  modified  as  to  enwrap  the 
tender  parts  in  the  form  of  tough  resistant  scales.  Ex- 
amples of  this  kind  might  be  cited  at  great  length.  In 
acting  in  this  way,  plants  have  shown  themselves  to  be 
wise  economists,  for  it  is  certainly  moving  along  lines  of 


FIG.  67. 

Shoot  of  Solanum  jasminoi- 
des,  showing  the  leaf  peti- 
oles acting  as  tendrils. 
After  GRAY. 


138  Introduction  to  Botany. 

least  resistance  to  modify  old  members  rather  than  to  pro- 
duce entirely  new  ones. 

110.  Characteristics  of  Morphological  Elements.  —  Since 
there  is  such  diversity  in  form  as  well  as  in  function  of 
roots,  stems,  and  -  leaves,  how  are  we  to  tell  when  we  are 
dealing  with  these  members  ?     By  a  comparative  study,  we 
find  that  there  are  certain  characters  which  appear  so  fun- 
damental as  to  furnish  reliable  evidence   for  recognizing 
the  members  to  which  they  belong.     Thus,  roots  are  out- 
growths from  stems  or  from  other  roots,  arid  do  not,  as  a 
rule,  arise  in  definite  order  or  definite  angular  divergence, 
except  in  the  case  of  the  secondary  roots  of    seedlings ; 
and  although  they  may  bear  adventitious  buds,  they  do  not 
directly  bear  leaves.     Stems  directly  bear  roots,  leaves,  and 
buds ;  and  most  lateral  stems  arise  either  in,  or  just  above, 
the  axils  of  leaves.     Leaves  are  borne  directly  on  stems ; 
they  have  a  definite  angular  divergence,  and  they  commonly 
bear  buds  in  their  axils.    Mere  outgrowths  of  the  epidermis, 
or  bark,  such  as  hairs  and  prickles,  differ  structurally  from 
the  morphological  elements  in  containing  none  of  the  parts 
of  a  vascular  bundle,  such  as  wood  fibers  and  tracheal  tubes. 
Whatever  form,  size,  structure,  color,  or  function  a  member 
may  have,  if  it  possess  a  set  of  characteristics  as  above 
stated  we  may  classify  it  accordingly. 

111.  Modified  Roots.  —  Roots  are  very  commonly  modi- 
fied to  serve  as  storehouses  for  nourishment ;  in  such  cases 
they  consist  for  the  most  part  of  thin-walled  tissues,  to  and 
from  which  the  reserve  materials  can  readily  pass  in  solu- 
tion.    The  dahlia  and  sweet  potato  afford  familiar  exam- 
ples of  roots  of  this  kind.     In  our  western  plains,  Ipomcea 
leptophylla  has  a  storage  root  weighing  from    10   to    100 
pounds.     The  climbing  roots  of  the  trumpet  creeper  occur 
in  clusters  at  the  nodes,  while  those  of  the  poison  ivy  occur 


Modified  Parts. 


139 


FIG.  68. 
Artichoke  tuber.    After  GRAY. 


in  two  almost  continuous  rows 
(see  Fig.  17).  In  these  cases, 
the  real  nature  of  the  roots 
is  not  much  masked.  The 
aerial  roots  of  orchids  and 
the  parasitic  roots  of  Cuscuta, 

although  modified  for  absorption  under  special  conditions, 
have  still  retained  much  of  the  appearance  of  typical  roots. 
The   supporting   roots  of   the 
banyan,     however,     extending 
to     the     ground,     have     the 
general  appearance  of  stems, 
but  their  identity  is 
easily  determined  by 
the      method      and 
place    of    their    ori- 
gin on  the  branches. 
112.     Modified 
Stems.  —  Stems   are 
frequently    modified 
to  grow  beneath  the 
surface,    and    there 
attain     considerable 
size  for  the  purpose 
of     storage ; 
the  potato 
and  artichoke 
are  good  ex- 
amples.    Al- 
though grow- 
ing   beneath 
the      ground 
like  roots,  and 


FIG.  69. 


Nelumbo  lutea.  v,  a  tuber  which  has  survived  the  winter;  x 
and  w,  horizontal  offshoots  growing  beneath  the  mud,  serv- 
ing the  purpose  of  multiplication ;  y,  shoot  growing  deeper 
preparatory  to  the  thickening  of  some  of  its  internodes  for 
the  purpose  of  storage,  as  in  v.  The  horizontal  lines  be- 
neath the  leaves  indicate  the  surface  of  the  water. 


140  Introduction  to  Botany. 

having  a  function  quite  different  from  that  of  typical 
stems,  their  morphological  nature  is  made  clear  by  their 
much  reduced  scale  leaves,  in  the  axils  of  which  buds  occur 
(see  Fig.  68).  Such  modified  stems  also  have  a  reproduc- 
tive function,  since,  after  they  have  survived  the  winter, 
their  buds  develop  into  new  shoots.  Stems  which  are 
modified  for  the  purpose  of  multiplication  are  illustrated 
by  the  above-ground  runners  of  the  strawberry  and  the 
underground  runners  of  the  goldenrod.  The  yellow  water 
lily,  Nelumbo  lutea,  affords  an  example  of  a  stem  which  is 
at  first  slender,  and  runs  along  in  the  mud  beneath  the 
water  for  the  purpose  of  multiplication,  and  later  becomes 
much  enlarged  in  certain  of  its  internodes  for  the  purpose 
of  storage  (see  Fig.  69). 

The  leaflike  structures  of  Ruscus  are  really  stems,  as  is 
shown  by  the  fact  that  they  do  not  bear  buds  in  their  axils, 
but  are  themselves  borne  in  the  axils  of  scales  which  have 
a  regular  angle  of  divergence  on  the  main  stem ;  the 
scales  being,  therefore,  morphologically,  leaves,  and  the 
leaflike  structures,  stems.  But  we  have  still  further  evi- 
dence, for  the  leaflike  structures,  termed  cladophylls,  bear 
flowers  in  the  axils  of  scales  that  are  evidently  leaves  (see 
Fig.  70).  To  sum  up  the  evidence:  The  cladophyll  is 
borne  in  the  axil  of  a  leaf,  and  itself  bears  a  leaf  and 
flowers.  The  evidence  is,  therefore,  strong  that  it  is  a 
stem.  The  fact  that  it  looks  like  a  leaf  and  performs  the 
photosynthetical  function  of  a  leaf  should  not  be  taken  as 
evidence  that  it  is  not  a  stem,  for  we  have  already  seen 
that  the  forms  of  plant  members  can  vary  indefinitely,  and 
that  they  may  be  put  to  a  variety  of  uses.  The  green, 
thick  stems  of  cacti  perform  the  double  function  of  storage 
and  photosynthesis,  while  the  leaves  have  become  reduced 
to  spines  that  have  entirely  lost  their  normal  function  of 
photosynthesis. 


Modified  Parts. 


141 


We  can  only  conjecture  how  such  modifications  of  form 
and  changes  of  function  have  come  about.  In  the  case  of 
cacti,  we  can  see  that  the  reduction  of  the  leaves  and  the 
thickening  of  the  stems 
have  fitted  them  to  in- 
habit desert  regions  by  a 
reduction  of  the  tran- 
spiring surface,  and  an 
increase  of  the  water- 
storage  tissues,  of  which 
the  bulk  of  the  plant  con- 
sists. In  the  case  of 
Ruscus,  it  may  be  that 
some  time  back  in  its 
ancestry  it  became  de- 
sirable to  reduce  tran- 
spiration on  account  of 
scarcity  of  water,  or  in- 
ability to  absorb  the  water 
because  of  its  saltiness, 
or  because  of  the  low 
temperature  of  the  soil 
(see  the  Chapter  on  Ad- 
aptation to  environment); 

under  which  conditions  the  plants  with  the  smallest  leaves 
might  have  fared  the  best  and  produced  the  greatest  num- 
ber of  offspring.  Then  it  might  have  come  about  in  the 
course  of  time  that  the  species  was  represented  by  indi- 
viduals whose  leaves  were  mere  scales.  Later,  the  condi- 
tions might  have  changed  so  that  water  could  be  more 
readily  obtained ;  it  would  then  have  been  desirable  to 
increase  surfaces  for  photosynthesis,  but  the  scale  leaves, 
being  poorly  nourished  and  reduced  members,  would  have 


FIG.  70. 


Shoot  of  Ruscus  hypoglossum,  showing  leaf- 
like  stems  or  cladophylls.    After  K.ERNER. 


142  '  Introduction  to  Botany. 

been  unable  to  produce  variations  from  which  a  selection 
of  suitable  forms  could  be  made.  The  better-nourished 
stems,  however,  would  have  been  able  to  do  this,  and 
finally  the  forms  which  we  now  see  could  have  been 
evolved.  This  description  is  of  course  conjectural,  and 
may,  or  may  not,  approximate  the  true  events. 

113.  Modified  Leaves.  —  Leaves  modified  for  storage  are 
found  in  the  scales  of  the  bulbs  of  onion,  in  the  thicker 
scales  of  tiger  lily  bulbs,  and  in  the  leaves  constituting  the 
cabbage  head.     The  fleshy  leaves  of  Agave  Americana  are 
storehouses  of  water  and  reserve  food,  while  at  the  same 
time  they  carry  on  the  normal  constructive  functions  of 
ordinary  leaves.     The  thick   leaves    of   succulent   plants, 
such  as  Mesembryanthemum  and  Sedum,  serve  as  store- 
houses for  water.     Leaves  which  have  been  modified  to 
serve  a  protective  function  are  seen  in  bud  scales,  and  in 
the  spines  of  cacti,  and  in  barberry.     Parts  of  leaves  which 
have  been  modified  to  form  tendrils  for  climbing,  we  find 
in  Solatium  jasminoides,  the  garden  pea,  etc. 

We  have  already,  in  the  last  chapter,  become  acquainted 
with  leaves  which  have  motor  organs,  digestive  glands, 
sensitive  hairs,  etc.,  for  the  capture  of  insects.  There  are 
other  modified  forms  of  leaves  which  entrap  insects  and 
apparently  use  them  for  food.  These  are  the  pitchers  of 
the  pitcher  plants  and  allied  forms,  and  the  bladderlike 
traps  of  the  bladderwort.  In  these  cases,  the  modifications 
are  so  great  and  their  adaptation  as  traps  is  so  wonderful 
that  they  deserve  a  somewhat  detailed  description. 

114.  Pitcher   Plants. —  The   pitcher   plants  (Nepenthes) 
are  natives  of  the  old  world  tropics.     The  pitcher  is  borne 
at  the  end  of  a  slender  prolongation  of  the  petiole,  and  is 
probably  itself  a  part  of  the  petiole  which  has  grown  out 
in  the  enlarged  tubular  or  pitcher  form.     At  the  top  of  the 


Modified  Parts. 


pitcher  is  a  lid  (see  Fig.  71),  which  may  correspond  to  the 
blade  of  the  leaf.  The  lid,  in  the  mature  pitchers,  stands 
open,  and  may  serve  as  an  attraction  for  insects.  The 
border  of  the  mouth  of  the  pitcher  is  rolled  inward  and 
downward,  and  often  there  are 
stout  teeth  extending  downward 
on  the  inner  edge  of  this  border. 
Honey  glands  occur  on  the  out- 
side of  the  pitcher,  on  the  in- 
rolled  border,  and  on  the  inner 
surface  of  the  lid;  by  this  means 
insects  which  alight  on  any  por- 
tion of  the  pitcher  are  lured  to 
the  edge  of  the  open  mouth. 
Once  over  the  border,  the  insect 
slips  into  the  pitcher,  which  con- 
tains a  fluid  having  digestive 
properties,  and  so  the  insect  be- 
comes digested  and  absorbed. 

The  pitcher  plant  called  Dar- 
lingtonia  shows  a  still  greater 
degree  of  modification.  In  this 
plant  the  top  of  the  pitcher 
arches  over  so  that  the  mouth 
is  directed  downward  (see  Fig. 
72),  while  extending  beyond  the 
border  of  the  opening  is  a  bi- 
parted,  brightly  tinted  expansion  somewhat  in  the  form  of 
a  pennant,  which  no  doubt  acts  as  an  attraction  to  insects. 
The  arched  dome,  or  helmet,  at  the  top  of  the  pitcher 
is  marked  with  red,  and  studded  over  with  spots  desti- 
tute of  color,  so  that  the  light  can  shine  through  them  as 
through  a  window.  Nectar  glands  on  the  outer  surface  of 


FIG.  71. 
Nepenthes  villosa.    After  KERNER. 


144 


Introduction  to  Botany. 


the  pitcher  and  under  surface  of  the  pennant  lure  both 
creeping  and  flying  insects  to  the  mouth  of  the  pitcher, 
and  after  they  have  passed  beyond  the  incurved  border, 

which  they  are  likely  to  do,  they 
meet  with  a  smooth  surface 
to  which  it  is  impossible  for 
them  to  cling,  and  are  precipi- 
tated to  the  bottom  of 
the  pitcher,  where  a  di- 
gestive secretion  awaits 
them.  The  attempts  of  creeping 
insects  to  crawl  out  of  the 
pitchers  are  frustrated  by  stiff, 
downward-pointing  hairs. 
Winged  insects  can  fly  upward, 
but  instead  of  finding  the  open- 
ing they  are  attracted  by  the 
transparent  spots  in  the  over- 
arching helmet,  against  which 
they  vainly  beat  until  they  be- 
come exhausted  and  fall  to  the 
bottom,  where  they  become  im- 
mersed in  the  digestive  fluid. 
The  pitcher  plant  known  as 
Sarracenia  variolaris,  which  is  common  in  the  southern 
states,  although  not  so  elaborate,  has  essentially  the  same 
devices  as  Darlingtonia,  for  alluring  and  entrapping  in- 
sects. 

Investigations  thus  far  leave  us  in  doubt  whether  the 
main  function  of  these  pitchers  is  the  capture  of  insects 
for  the  food  of  the  plant,  or  whether  they  are  primarily 
water  reservoirs  to  hold  water  that  has  been  exuded  from 
the  plant  itself,  or  caught  from  the  rain  in  those  cases 


FIG.  72. 

Darlingtonia  Californica. 
GEDDES. 


After 


Modified  Parts. 


where  the  pitchers   stand   open.     Insect-catching,  at  any 
rate,  appears  to  be  one  of  their  important  functions. 

It  is  not  easy  to  conceive  how  the  modifications  into 
pitchers  have  come  about.  We  know  that  there  is  in 
plants  a  capacity  to  vary  which  is  apparently  stimulated  to 
activity  by  both  internal  and  external  causes. 
Useful  variations  would  be  likely  to  persist 
and  become  more  pronounced  by  the  produc- 
tion of  more  numerous  and  stronger  offspring, 
of  which  those  having  the  most  useful  varia- 
tions would  finally  predominate,  because  bet- 
ter fitted  to  contend  for  soil,  air, 
and  sunlight.  But  how,  in  this  case, 
the  variation  became  started  along 
the  line  of  pitcher  formation  lead- 
ing finally  to  the  win- 
dowed dome,  slip- 
pery surfaces,  and 
detaining  down- 
ward-pointing hairs 
can  only  be  an- 
swered with  conjec- 
tures. 

115.Bladderworts. 
-  Not  less  wonder- 
ful are  the  modified 
leaves  of  the  common  Utricularia  or  bladderwort.  This 
is  an  immersed,  floating  water  plant  (see  Fig.  73,  A). 
Some  of  its  leaves  are  much  divided  and  threadlike,  and 
others  are  modified  in  the  form  of  little  bladderlike  traps 
adapted  to  catching  very  minute  water  animals.  The  en- 
trance into  the  cavity  of  the  bladder  is  provided  with  a 
door  which  swings  inward,  but  never  outward,  because  its 


FIG.  73. 

Utricularia  grafiana.  A,  showing  flower  rising  above 
the  water,  and  below  the  water  finely  divided  foliage 
leaves,  and  bladderlike  leaves.  After  KERNER. 
B,  longitudinal  diagram  of  a  bladder  leaf  of  Utricu- 
laria vulgaris,  showing  trap  door  opening  inwards. 


146  Introduction  to  Botany. 

free  edge  swings  against,  and  overlaps  on  the  inside,  the 
thickened  lower  border  of  the  opening  (see  Fig.  73,  B}. 
Stiff  hairs  fringe  the  opening  on  the  outside,  and  probably 
offer  a  place  of  refuge  for  small  water  crustaceans  and 
various  small  larvae  when  pursued  by  larger  animals.  The 
little  animals  are  apt  to  push  their  way  farther  into  the 
bladder,  the  door  of  which  easily  rises  to  admit  them,  but 
never  swings  outward  to  permit  their  escape.  Finally  they 
die,  become  disintegrated  by  bacteria  inhabiting  the  in- 
terior of  the  bladders,  and  the  soluble  products  of  their 
decomposition  are  absorbed  by  the  inner  surface  of  the 
bladder,  and  thence  distributed  to  the  rest  of  the  plant. 
Experiments  seem  to  show  that  the  animal  food  thus  ob- 
tained is  useful  in  the  nutrition  of  the  bladderwort. 


CHAPTER  VIII. 
FLOWERS. 

PROVIDING  MATERIALS. 

If  the  work  in  botany  is  begun  soon  after  the  Christmas  holidays, 
the  early  wild  flowers  will  probably  begin  to  appear  by  the  time  the 
work  already  outlined  has  been  completed.  When  there  is  doubt  of 
the  availability  of  wild  flowers  at  the  required  time,  material  placed  in 
formalin  the  previous  summer  should  be  at  hand ;  or  arrangements 
should  be  made  with  a  greenhouse  for  forms  which  can  be  supplied  in 
abundance,  such  as  sweet  alyssum,  Chinese  primroses,  Freesias,  Tri- 
teleias,  and  single  hyacinths. 

It  is  desirable  to  select  for  preservation  in  formalin  flowers  which  are 
somewhat  stiff  and  leathery,  such  as  those  of  the  honeysuckle,  trumpet 
creeper,  Yucca,  tiger  lily,  and  some  of  the  larger  composites.  The 
Yucca  is  particularly  good  for  introducing  the  student  to  the  structure 
of  flowers,  since  all  of  its  parts  are  large  and  simple  in  construction, 
and  it  has  the  further  advantage  of  being  one  of  the  most  interesting 
flowers  in  the  method  of  its  cross  pollination.  (See  page  196.)  As 
soon  as  the  structure  of  a  few  typical  flowers  has  been  learned,  wherever 
practicable,  entire  plants  should  be  provided  for  the  study  of  plants  as 
a  whole. 

When  flowers  have  become  sufficiently  abundant  out  of  doors  to  admit 
of  choice,  only  those  forms  should  be  selected  which  show  well  some 
definite  facts  of  floral  structure,  adaptation  to  pollination,  or  relation- 
ships such  as  are  exhibited  by  the  different  species  of  a  genus.  No- 
where in  an  introductory  course  in  botany  is  the  limited  time  usually 
available  more  in  danger  of  being  misapplied  than  in  the  promiscuous 
study  of  flowers  without  reference  to  some  definite  problem. 

To  illustrate :  Anemone  or  Ranunculus  might  be  chosen  to  show  a 
simple  type  of  flower,  with  parts  distinct  and  regular ;  larkspur,  to  bring 
out  relationship  to  the  simple  Anemone  type,  but  with  profound  modi- 

147 


148  Introduction  to  Botany. 

fications  to  insure  cross  pollination  (flowers  of  different  ages  are 
necessary  to  show  all  that  this  flower  has  to  teach)  ;  Oxalis,  to  show 
special  devices  for  cross  pollination,  each  student  being  supplied  with 
the  two  forms  of  Oxalis  violacea,  for  instance,  which  may  be  found 
growing  together  in  the  same  patch ;  all  obtainable  species  of  violets, 
to  exhibit  special  devices  for  cross  pollination,  and  considerable  varia- 
tions in  the  foliage  and  habits  of  plants  having  flowers  of  essentially 
identical  structure.  This  comparative  study  of  violets  is  excellent  in 
showing  how  the  flower,  more  than  any  other  structure,  gives  the  most 
reliable  clews  to  plant  relationships. 

It  is  best  to  have  the  whole  class  at  one  time  working  on  the  same 
kind  of  flower,  in  order  that  the  discussions  and  blackboard  demonstra- 
tions, which  are  frequently  desirable,  may  be  founded  on  the  experience 
of  all  of  the  students.  The  material  should  therefore  be  chosen  in  time 
to  have  an  abundance  provided  for  each  day's  work. 


OBSERVATIONS. 

119.  Make  a  drawing  of  the  flower,  showing  its  position 
on  the   branch   and  its  relation  to  outgrowths  from  the 
branch  (a,  Fig.  74). 

1 20.  Dissect  the  flower  into  its  separate  parts,  and  make 
sketches  showing  the  form  of  each  (</,  f,  gt  h,  i,  /). 

121.  Make  a  drawing  of  the  flower  on  a  larger  scale,  if 
necessary,  showing  the  sets  of  organs  in  right  number  and 
proportion  (b). 

It  is  best  to  sketch  in  lightly  the  form  of  the  flower 
before  drawing  its  details.  This  can  be  most  easily  and 
accurately  done  by  drawing  first  a  circle,  ellipse,  square, 
or  rectangle  as  a  form  guide,  for  most  flowers  conform  in 
general  contour  more  or  less  to  one  of  these  figures  (see 
diagrams  of  Fig.  75).  A  flower  whose  general  outline  is 
circular  when  held  before  the  observer  with  axis  horizontal, 
as  in  H,  will  appear  more  and  more  narrowly  elliptical  as 
its  axis  is  shifted  toward  the  vertical,  as  in  /  and  J.  The 


m 


FIG.  74. 

Study  of  Capsella  bursa-pastoris  (Shepherd's  purse).  A  type  page  of  Student's 
Laboratory  Book  :  a,  entire  plant ;  d,  a  flower  enlarged  ;  c,  longitudinal  diagram 
of  an  open  flower ;  d,  cross  diagram  of  a  flower ;  e,  longitudinal  diagram  of  a  bud ; 
/  a  petal ;  g,  a  sepal ;  h,  a  stamen  before  the  opening  of  the  anther ;  i,  a  stamen 
after  the  anther  has  broken  open  to  discharge  the  pollen ;  j,  a  pistil  enlarged, 
with  nectaries  at  its  base;  k,  an  ovule  enlarged;  /,  the  fruit  or  ripened  pistil; 
m,  fruit  dehiscing. 


5o 


Introduction  to  Botany. 


FIG.  75. 
Guide  forms  for  drawing  flowers.    See  text. 


same  thing  is  illustrated  for  a  cruciferous  flower  in  E,  Ft 

and  G.  Compare  also  the 
diameters  of  the  three 
faces  of  diagram  K. 

In  drawing  long  or 
much-curved  leaves  it  is 
a  good  plan  to  draw  the 
midrib  first,  and  so  estab- 
lish the  total  length  and 
right  curvature;  then  at 
a  point  on  the  midrib 
where  the  leaf  is  broadest 
a  line  should  be  drawn  at 
right  angles  with  the 
midrib,  establishing  the 
breadth  of  the  leaf  in 

right  proportion  to  the  length.     Last,  the  outline  of  the 

leaf  should  be  drawn,  and  the  venation  put  in  (d,  Fig.  76). 

If   the   leaf  is  divided  or  com- 
pounded, the  general  outline  of 

the  leaf  and  the  veins  or  midribs 

of  the  leaflets  should  be  made  as 

already   directed,  and   then  the 

outlines   of    the   leaflets  should 

be  drawn,  as  in  e,  Fig.  76. 

All     guide     lines    should,    of 

course,   be   drawn   with   a   very 

light  touch,  and  erased  after  the 

flowers    and    leaves    have   been 

outlined. 

122.    With  a  sharp  knife  make  cross  and  vertical  sections 

of  the  ovary,  and  draw  to  a  scale  sufficiently  large  to  show 

the  manner  of  attachment  of  the  ovules  (in  c  and  d,  Fig.  74). 


FIG.  76. 

Guide  forms  for  drawing  leaves. 
See  text. 


Flowers.  151 

123.  Make  cross  and  vertical  diagrams  of  the  flower  as 
in  c  and  d,  Fig.  74,  showing  clearly  the  number,  relation- 
ships, and  relative  positions  of  the  parts.  The  cross  dia- 
gram shows  the  number  of  the  parts  and  their  relative 
positions,  while  the  vertical  diagram  shows  the  attach- 
ment, direction,  and  to  a  certain  extent  the  form  of  the 
parts. 

In  drawing  the  cross  diagrams  a  pair  of  cheap  dividers 
carrying  a  lead  pencil  will  be  a  great  help  in  placing  the 
different  whorls  of  parts  symmetrically.  The  guide  circles 
should  be  made  with  a  light  touch,  making  first  the  central 
circle  a,  A,  Fig.  77,  for  the  ovary,  and  then  the  circles  b^ 
c,  and  d  for  locating  the  stamens,  petals,  and  sepals.  Draw 
dotted  or  very  faint  lines,  as  in  B  and  C,  to  locate  the 
position  of  the  walls  of  the  ovary.  Then  outline  the  cavi- 
ties of  the  ovary,  taking  care  to  show  the  right  relative 
thickness  of  the  outer  and  partition  walls  of  the  ovary,  as 
in  D  and  E.  If  the  placentae  are  central,  as  in  D,  the 
place  of  attachment  of  the  ovules  should  be  left  blank  (see 
cavity  e,  D}  until  the  cavities  are  outlined ;  then  the  ovules 
are  to  be  outlined  by  continuing  the  ends  of  the  interrupted 
line  (/  and  g,  D).  If  the  placentae  are  parietal,  proceed 
according  to  diagram  E. 

Place  points  on  the  outer  circles  to  locate  the  positions 
of  the  stamens  and  the  centers  of  the  petals  and  sepals,  as 
in  A.  If  the  dividers  are  set  to  swing  guide  circles  having 
diameters  the  same  as  those  of  the  half  circles  on  the  pro- 
tractor (Fig.  84),  the  guide  circles  may  quickly  be  divided 
into  the  required  number  of  equal  parts.  Suppose,  for 
example,  that  the  guide  circle  has  the  same  diameter  as 
the  half  circle  c,  and  it  is  desired  to  divide  the  guide  circle 
into  five  equal  parts ;  place  one  point  of  the  dividers  at 
c  on  the  zero  line  and  the  other  on  the  circumference  c, 


152 


Introduction  to  Botany. 


where  the  72°  line  would  intersect  it.     With  the  dividers 
thus  set  space  off  the  guide  circle  into  five  equal  parts. 


CD 


G  H  I 

FIG.  77. 
Method  of  making  floral  diagrams.    See  text. 


In  the  cross  diagram  outline  the  anthers  as  they  appear 
in  the  cross  section,  having  the  lobes  face  outward  (b,  F) 
or  inward,  as  the  case  may  be  in  the  specific  flower.  Rep- 
resent the  sepals  and  petals  as  crescentic  figures  (c  and 


Flowers.  153 

d,  F\  having  them  sustain  the  same  relation  to  each  other 
as  to  overlapping  as  observed  in  the  flower. 

In  drawing  the  longitudinal  diagram  make  first  a  faint 
guide  line,  G,  having  the  same  relation  to  the  vertical  as 
the  axis  of  the  flower  has  in  its  natural  position  on  the 
plant.  The  guide  line  is  placed  vertically  in  G,  but  in 
violet,  larkspur,  Baptisia,  etc.,  it  would  be  at  some  angle 
with  the  vertical.  The  position  which  the  flower  assumes 
often  has  an  important  bearing  on  pollination.  The  mean- 
ing of  the  irregularities  of  irregular  flowers  frequently  can- 
not be  understood  until  the  direction  taken  by  the  axis  of 
the  flower  is  known.  In  the  case  of  a  flower  having  a 
definite  upper  and  under  side,  both  the  longitudinal  and 
the  cross  diagram  should  take  note  of  this  so  that  the 
structurally  under  side  of  the  diagram  is  directed  toward 
the  bottom  of  the  page  and  the  upper  side  toward  the  top. 
Space  off  on  this  guide  line  the  relative  lengths  of  ovary 
and  style,  and  on  either  side  locate  with  points  the  greatest 
diameter  of  the  ovary,  as  shown  in  G.  Then  outline  the' 
pistil,  as  in  H,  and  set  points  a  and  b  to  fix  the  relative 
lengths  of  anther  and  filament,  and  points  c,  d,  and  e  to 
mark  the  height  and  greatest  spread  of  the  corolla  and 
calyx.  At  the  base  of  the  ovary  continue  the  outline 
upward  to  form  the  stamen,  as  in  /,  and  continue  the 
outer  line  of  the  filament  upward  at  the  base  to  form  the 
petal,  as  in  /  and  Jt  and  continue  in  like  manner  to  form 
the  sepal  as  in  K.  Construct  the  other  half  of  the  dia- 
gram in  the  same  manner. 

In  outlining  the  cavities  of  the  ovary,  if  the  placentae 
are  central,  draw  first  the  inner  border  of  the  outer  wall, 
as  in  the  right  half  of  the  pistil  of  diagram  K,  and  then 
continue  this  line  to  form  the  ovules,  as  in  the  left  half. 
If  the  placentae  are  parietal  and  there  is  more  than  one 


'54 


Introduction  to  Botany. 


cavity  in  the  ovary,  draw  the  line  near  the  center,  fixing 
the  thickness  of  the  central  partition  wall,  as  in  the  right 
half  of  diagram  L,  and  then  continue  this  line  to  form  the 
ovules,  as  in  the  left  half.  Erase  guide  lines  when  the 
diagrams  are  completed. 

By  constructing  the  diagrams  as  here  directed  the  parts 
of  the  flower  will  be  represented  as  continuous  tissues,  as 
they  should  be.  There  should  not,  for  instance,  be  a  line 
separating  the  ovules  from  the  placentae,  or  the  pistil, 
stam'ens,  petals,  and  sepals  from  the  receptacle.  Unless 
one  has  good  judgment  of  distance  and  proportion  the 
guide  lines  and  points  here  suggested  will  be  found  neces- 
sary for  the  required  degree  of  accuracy. 

The  chief  features  of  irregularities  in  irregular  flowers 
should  be  indicated  in  the  cross  and  longitudinal  diagrams. 

Taking  the  violet  for  an  ex- 
ample :  in  the  longitudinal  dia- 
gram the  spur  of  the  lower 
petal,  one  of  the  nectaries  pro- 
jecting into  the  spur,  the  one- 
sided stigma,  and  the  anthers 
with  sterile  tips  conniving 
around  the  style  should  be 
shown  in  right  proportion  and 
position.  In  the  cross  diagram 
the  spur  of  the  lower  petal  and 
the  nectaries  projecting  into  it 
should  be  shown,  and  the  fact 
that  the  stamens  are  syngene- 
sious  should  be  shown  by  the 

close  proximity  of  the  anthers  and  the  continuous  line  from 
the  back  of  one  anther  to  that  of  another  (see  Fig.  78). 
In  the  larkspur,  to  take  another  example  of  an  irregular 


A,  longitudinal,   and  Bt   cross  dia- 
gram of  the  flower  of  the  violet. 


Flowers. 


ISS 


flower,  the  upper  sepal  with  its  long  spur  and  one  of  the 
upper  petals  with  its  spur  projecting  into  that  of  the  upper 
sepal  may  be  shown  in  the  longitudinal  diagram,  as  in  A, 
Fig.  79-  In  tne  cross  diagram  the  fact  that  the  upper 
sepal  and  the  two  upper  petals  each  form  a  tube  below 
may  be  indicated  by  dotted  lines,  as  in  B,  Fig.  79. 


FIG.  79. 

A,  longitudinal,  and  B,  cross 
diagram  of  the  flower  of 
the  larkspur. 


Diagrams  of  composite  flowers.  A,  cross 
diagram  of  a  flower  with  ligulate  co- 
rolla; B,  cross  diagram  of  a  flower 
with  tubular  corolla;  C,  longitudinal 
diagram  of  a  flower. 


The  method  of  diagraming  composite  flowers  is  shown 
in  Fig.  80.  A  is  a  cross  diagram  of  a  flower  with  ligu- 
late corolla.  The  stamens  are  shown  to  be  syngenesious 
by  lines  uniting  the  backs  of  the  anthers,  and  the  radiating 
lines  from  the  backs  of  the  anthers  signify  that  the  sta- 
mens are  inserted  on  the  corolla.  The  dotted  line  complet- 
ing the  petaline  whorl  indicates  that  the  corolla  is  tubular 


i56 


Introduction  to  Botany. 


below.  In  the  sepaline  whorl  the  five  triangular  figures 
are  meant  to  indicate  that  in  all  probability  five  sepals 
are  represented  in  the  circle  of  hairs,  scales,  awns,  etc., 
collectively  termed  pappus  in  these  flowers. 

B  is  a  cross  diagram  of  a  flower  with  tubular  corolla. 
Diagram  C  is  a  type  of  either  ligulate  or  tubular  flower. 
These  diagrams  are  to  be  considered  as  types  simply,  which 
the  student  can  adapt  to  the  flower  in  hand. 

The  fact  that  the  stamens  are  monadelphous  or  united 
by  their  filaments  into  one  group  may  be  shown  in  cross 
section  by  lines  joining  the  anthers  at 
the  middle  of  their  contiguous  faces, 
as  in  By  Fig.  81.  Here  also  the  radi- 
ating lines  from  the  backs  of  the 
anthers  indicate  that  the  stamens  are 
united  to  the  petals.  The  longitudinal 
diagram  A  shows  that  the  stamens  are 
inserted  near  the  bases  of  the  petals, 
and  that  the  anthers  are  borne  at 
different  heights  on  the  tube  formed 
by  the  union  of  the  filaments. 

The  type  diagrams  here  given,  to- 
gether with  those  of  Fig.  123,  will  serve 
A,  longitudinal,  and  B,   to  show  the  student  a  concise  method 
cross  diagram  of  a  mai-    of  representing  the  various  irregulari- 

low  flower.  . .  . 

ties  and  unions  of  parts. 

124.  With  colored  pencils  tint  the  calyx  in  the  diagrams 
green,  corolla  yellow,  •  receptacle  orange,  ovary  and  style 
blue,  stigma  purple,  anther  red,  and  ovules  red.  The 
anthers  and  ovules  are  widely  enough  separated  not  to  be 
confused  by  having  the  same  color.  By  giving  them  the 
same  color  it  is  meant  to  signify  that  they  both  contain 
essential  organs  for  reproduction,  namely,  the  anthers  con- 


Flowers. 

taining  the  pollen  which  supplies  the  sperm,  and  the  ovules 
containing  the  eggs. 

125.  Study  the  appearance  of  the  sets  of  parts  in  bud 
and  in  blossom,  and  record  with  drawings  and  notes  the 
changes  which  take  place  from  bud  to  fruit  (see  drawings 
in  Fig.  74).  Work  out  these  points  according  to  the  fol- 
lowing outline :  — 

A.  (i)  The  manner  in  which  the  calyx  affords  protection 
to  the  other   parts   of   the  bud,  by  its  character  and   its 
method  of  enwrapping  them.     (2)  The  changes  in  the  char- 
acter and  functions  of  the  calyx.     Does  it  persist  through 
the  continuance  of  the  rest  of  the  flower,  or  even  through 
the  formation  of  the  fruit  ? 

B.  (i)  The  position  of  the  corolla  in  the  bud.     (2)  How 
the  petals  are  related  to  each  other,  and  how  they  enfold  the 
parts  within.    Does  the  corolla  in  the  bud  afford  any  protec- 
tion to  the  stamens  and  pistils  ?    (3)  How  the  petals  change 
in  size,  form,  texture,  and  color  as  the  bud  unfolds  ;  at  what 
stage  the  petals  seem  to  have  completed  their  mission. 

C.  (i)  The  positions  of  the  stamens  in  the  bud.     (2)  The 
changes  in  the  position  and  size  of  the  stamens  as  the  bud 
unfolds.     (3)  At  what  stage  of  the  flower  the  anthers  open 
and  discharge  their  pollen.     Do  the  stamens  change  their 
position  with  reference  to  the  stigma  as  the  bud  unfolds  ? 
Do  these  positions  seem  to  prevent  or  insure  self  fertiliza- 
tion ? 

D.  (i)  The  changes  in  the  size  and  position  of  the  style. 
(2)  The  stage  at  which  the  stigma  has  sufficiently  developed 
and  has  assumed  the  right  position  to  receive  the  pollen. 
Could   self-pollination  take  place  in  the  bud  ?     Are  the 
changes  undergone  by  the  style  and  stigma  in  the  interest 
of  cross  or  self-fertilization  ? 

E.  Whether  the  position  taken  by  the  open  flower  has 


158 


Introduction  to   Botany. 


any  direct  bearing  on  pollination,  and  whether  in  the  open 
flower  the  relation  of  calyx  or  corolla  to  the  stamens  and 

pistil  has  anything  to  do 
9      with  pollination. 

F.  If  there  are  irregu- 
larities of  structure  try 
to  find  their  significance. 
126.  Having  become 
familiar  with  the  method 
of  working  with  flowers, 
study  the  plant  as  a 
whole,  and  make  dia- 
grams to  show  the  habit 
of  plants,  and  the  man- 
ner in  which  the  flowers 
are  borne. 

In  showing  the  habit 
of    the    plant    and   the 
character   of    the    inflo- 
rescence,     conventional 
FlG  g2  forms     may     be     used. 

Conventional  diagrams  to   represent  a  leaf  /,    TllUS    l  °f  F[8'    82    maX 
flower  bud  o,  open  flower/,  fruit  q,  raceme  r,    Stand  for  a  leaf,  0  for  a 


either  cluster  to  the  right  and  left  of  the  cen-   flower,  and  q  f  Or  a  f  ruit. 
tral  flower  would  represent  a  simple  cyme.  T  T    .  ,     , 

Using  these  symbols, 

the  chief  types  of  inflorescences  may  be  represented  as  in 
diagrams  r  to  y  in  Figs.  82  and  83.  r  represents  a  raceme, 
in  which  the  axis  of  the  inflorescence  elongates  with  age, 
giving  rise  to  new  flowers  as  growth  in  length  proceeds, 
each  flower  having  its  own  stalk  or  pedicel,  s  represents 
a  spike  or  ament,  which  differs  from  a  raceme  in  having 
the  flowers  sessile  upon  the  common  axis,  x  is  a  diagram 


Flowers. 


I59 


FIG.  83. 

w,  a  crowded  cyme  or  fascicle ;  x,  a  corymb ; 
y,  an  umbel. 


of  a  corymb,  whose  older  flowers  differ  from  those  of  a 
raceme  in  having  their  pedicels  elongated  so  that  a  some- 
what flat-topped  flower  cluster  is  produced,  y  stands  for 
an  umbel,  having  the 
pedicels  of  nearly  equal 
length,  and  inserted  at 
about  the  same  height 
on  the  common  axis. 
u  represents  a  head  of 
the  composite  type,  and 
t  a  head  of  the  clover 
type  with  the  receptacle 
much  exaggerated. 

The  raceme,  spike, 
corymb,  umbel,  and  head 
are  called  indeterminate; 
they  have  this  feature  in  common,  that  the  older  flowers 
are  at  the  base  or  periphery,  and  the  younger  flowers  are 
at  the  apex  or  center  of  the  inflorescence. 

In  another  type  of  inflorescence  known  as  the  cyme  (y 
and  w)  the  terminal  or  central  flower  is  the  oldest.  This 
sort  of  inflorescence  is  termed  determinate,  since  the  com- 
mon axis  is  not  indefinite  in  elongation  as  in  the  raceme 
and  spike.  A  compact  cyme  like  that  of  the  Sweet  William 
is  called  a  fascicle,  and  one  that  is  still  more  compact  so  as 
to  simulate  a  head  is  termed  a  glomerule. 

127.  Tie  paper  bags  over  flowers,  so  that  neither  wind 
nor  insects  can  disturb  them,  and  note  whether  they  are 
able  to  achieve  self-fertilization. 

128.  Before  the  stamens  have  discharged  their  pollen, 
remove  them  from  a  flower,  and  then  by  means  of  a  camel's 
hair  brush  transfer  to  the  stigma  pollen  from  a  flower  of 
another  plant  of  the  same  kind.     Tie  a  bag  over  the  flower 


160  Introduction  to  Botany. 

and  allow  it  to  go  to  seed  in  this  way.  Tie  a.  bag  over 
another  flower,  while  it  is  yet  in  bud,  to  keep  foreign  pollen 
away,  and  when  the  flower  has  opened  pollinate  it  with  its 
own  pollen.  Replace  the  bag  and  allow  the  flower  to  go 
to  seed.  When  the  seeds  in  both  experiments  have  formed, 
compare  the  number  and  size  of  seeds  produced  by  self 
and  cross  fertilization.  The  larger  the  number  of  experi- 
ments of  this  kind  the  more  reliable  are  the  results. 

129.  Remove  the  petals  from  flowers  which    bees  are 
seen  to  visit  frequently,  and  note  whether  the  number  of 
the   visits  to  the   mutilated  flowers    is   influenced  by  the 
removal  of  the  colored  parts. 

130.  Record  the  behavior  of  bees  and  butterflies  in  ob- 
taining nectar  or  pollen  from  flowers,  noting  whether  these 
insects  would  be  apt  to  be  the  cause  of  cross  pollination. 

131.  Make  a  record  of  some  flowers  which  open  only  in 
the   nighttime.     Do  they  become   more  fragrant  at  that 
time  ?     Are  they  of  light  or  dark  hue  ?     What  particular 
sorts  of  insects  visit  them  ? 

132.  Make  a  record  of  some  flowers  which  are  open  only 
in  the  daytime.     After  closing  at  night  do  they  open  again  ? 

133-  Watch  the  behavior  of  the  stigmas  of .  catalpa 
flowers.  At  what  stage  in  the  development  of  the  flowers 
do  the  stigmas  spread  apart  ?  Do  you  find  both  open  and 
closed  stigmas  in  the  older  flowers?  Touch  the  open 
stigmas  with  a  brush  or  stick,  and  note  their  behavior. 
Dust  pollen  on  other  open  stigmas  and  note  the  result. 
Do  the  stigmas  behave  alike  in  both  cases  ?  The  experi- 
ment should  be  kept  under  observation  for  some  time  be- 
fore the  final  record  is  made. 

134.  Touch  the  bases  of  the  filaments  of  barberry 
flowers,  and  note  the  behavior  of  the  stamens.  Would 
pollination  be  likely  to  occur  without  the  aid  of  insects  ? 


1 62  Introduction  to  Botany. 


DISCUSSION. 

116.  Different  Methods  of  Reproduction.  —  The  reproduc- 
tion of  plants  may  take  place  either  asexually  or  sexually. 
In  the  former  process  a  greater  or  less  portion  of  the 
parent  plant  becomes  detached,  and  grows  to  be  an  inde- 
pendent individual.     With  some  instances  of  this  kind  we 
are  already  familiar.     The  reproduction  of  the  potato  by 
means  of  tubers,  of  the  sweet  potato  by  means  of  roots, 
and  artificial  reproduction  by  means  of  cuttings  and  grafts 
have  already  been  discussed  in  the  chapters  on  stems  and 
roots.     We  have  seen  that  portions  of  stems  and  roots, 
and   aggregations  of    stems   and    leaves  in   the   form   of 
buds,  as  seen  in  the  bulb  of  the  onion,  for  instance,  may 
serve  the  purpose  of  reproduction.     In  some  of  the  lower 
forms  of   plant  life   a   single   cell   may  serve   the   same 
purpose'. 

117.  Reproduction  in  Ulothrix.  —  In  Ulothrix  zonata  (see 
Fig.  85),  a  fresh-water  Alga,  the  protoplasts  of  the  cells 
which  constitute  the  body  of  the  plant  may  divide  to  form 
many  daughter   protoplasts,   which   break    out   from   the 
mother  cell  and  swim  about  in  the  water  by  means  of  four 
cilia;  after  a  time  these  motile  spores  come  to  rest,  and 
each  gives  rise,  by  cell  division,  to  a  multicellular  plant 
body  similar  to  the  one  from  which  it  sprang.     In  the 
same  plant  another  process  of  reproduction  may  also  take 
place.     A  protoplast  of  one  of  the  cells  of  the  plant  body 
may  divide  to  form  daughter  protoplasts  smaller  than  those 
just  described,  and  having  two  cilia  instead  of  four.     These 
swim  about  in  the  water  for  a  time,  but  finally  fuse  in  pairs 
to  form  a  spore,  which  by  cell  division  and  enlargement 
produces  a  plant  like  the  parent.     The  fusing  daughter 
protoplasts,  or  cells,  as  we  may  call  them,  may  be  considered 


Flowers. 


1 63 


as  sex  cells,  but  they  are  entirely  alike,  and  cannot  be  con- 
sidered as  distinctly  male  and  female. 

118.  Reproduction  in  Oedo- 
gonium.  —  In  Oedogonium, 
which  is  another  low  form  of 
plant  growing  in  water,  there 
is  a  very  marked  difference  in 
the  two  cells  which  unite.  By 
reference  to  Fig.  86  this  will 
be  made  clear.  The  plant 
body  consists  of  a  multicellular 
filament.  Certain  of  the  cylin- 
drical cells  of  the  filament  grow 
into  the  form  of  spheres  (termed 
oogonia ;  singular,  oogonium), 
and  become  gorged  with  food 
materials.  In  some  species 
others  of  the  cylindrical  cells 

divide     tO     form     shorter     Cells    Reproduction    in     Ulothrix    zonata. 
,  -,  i          j  •    •  j  *»  a  young  filament ;  2,  four  cells  of 

whose  protoplasts  also  divide      a  filament  whose  protopiasts  have 

each  tO  form  tWO  protoplasts  divided  to  form  small  zoospores, 
.  ...  .  seen  escaping  from  two  of  the  cells ; 

having  power  of  locomotion  by 
means  of  cilia.  These  pass 
through  openings  in  the  walls 
of  the  parent  cell,  swim  to 

and  enter  an  oogonium,  and  one  of  them  fuses  with  its 
protoplast.  A  thick  wall  is  now  formed  about  the  fused 
protoplasts,  and  the  body  thus  protected  is  known  as  a 
resting  spore.  After  a  time,  depending  to  a  certain  extent 
on  external  conditions,  the  resting  spore  divides  to  form 
four  ciliated  motile  bodies,  each  of  which  finally  grows  to 
be  a  filamentous  plant  like  the  parent.  In  Oedogonium, 
therefore,  sexuality  has  become  clearly  developed.  One 


FIG.  85. 


3,  protoplasts  escaping  to  form  large 
zoospores ;  4  and  .5,  the  fusion  of 
two  small  zoospores ;  6,  a  large 
zoospore.  After  DODEL-PORT. 


164 


Introduction  to  Botany. 


reproductive  cell  is  much  larger  than  the  other,  is  stored 
with  food  materials,  and  is  stationary,  while  the  smaller  re- 

productive cell  is  motile,  seeks 
the  larger  cell,  and  fuses  with 
it.  The  larger  cell  may  there- 
fore be  designated  the  female 
reproductive  cell  or  egg,  and 
the  smaller  cell  the  male  repro- 
ductive cell  or  sperm. 

119.  Functions  and  Relation- 
ships of  Floral  Structures.  - 
The  essential  parts  of  a  flower 
consist  of  the  sperms  and  the 
eggs,  and  the  organs  which 
bear  and  protect  them.  Figure 
87  is  a  diagrammatic  represen- 
tation of  a  typical  flower.  At 
b  is  a  sepal,  one  of  the  external 
members  of  the  flower,  which 
taken  collectively  constitute 
the  calyx.  The  calyx  enwraps 

Reproduction    in    Oedogomum   ctha-  J 

turn,     i,  a,  an  oogonium  in  which  is  the    Other    parts    of    the    flower 

borne  the  large  egg  cell;  b,  an  an-  .        fa     bud  and      iyes  them  SQme 
thendium  in  which  the  sperm  cell 

occurs;  2,  showing  the  sperm  cell  degree  of  protection,  and  some- 

$t&5ri£Z3z.  times  '*  is  brightly  colored  and 

ing  the  protoplasts  in  two  ceils  of  an  helps  to  make  the  flower  con- 

Oedoeonium     filament     ready    to  T,    • 

It  IS    not 


emerge  and  become  asexual  swarm    SplCUOUS. 

spores;  4,  an  asexual  swarm  spore.    fjO  the  production  of  seeds,  and 

After  PRINGSHEIM.  .  .  ,  . 

is  sometimes  wanting. 

At  c  is  a  petal.  The  petals  constitute  the  corolla  ;  they 
are  usually  white  or  brightly  colored  ;  in  the  bud  they 
enwrap  the  inner  members  and  thus  help  to  protect  them, 
and  in  the  open  flower  they  are  advertisements  to  insects, 


Flowers.  165 

humming-birds,  etc.,  which,  as  we  shall  see,  may  be  of 
service  in  the  production  of  seeds.  The  petals  are  not 
absolutely  necessary  to  reproduction,  and  are  often  wanting. 
At  d,  e  is  a  stamen,  made  up  of  d,  the  filament,  and  e, 
the  antJier.  The  anthers  contain  small  grains,  known  as 
pollen  grains,  which  produce  the  sperm,  and  are  therefore 
absolutely  necessary  to  the  production  of  seeds. 


FIG.  87. 

Longitudinal  diagram  of  a  Flower,  a,  the  receptacle;  b,  sepal;  c,  petal;  d,  fila- 
ment ;  e,  anther  (filament  and  anther  constitute  the  stamen)  ;  f,  ovary ;  g ,  style ; 
h,  stigma  (ovary,  style,  and  stigma  constitute  the  pistil)  ;  /,  pollen  tube  descend- 
ing through  the  style  to  the  ovule  ;  n,  cavity  of  the  ovary ;  /,  the  ovule  consisting 
of  the  stem  or  funiculus,  m  ;  two  coats  with  an  opening,  /£,  through  them  (micro- 
pyle)  at  the  lower  end;  the  nucellus,  o,  and  the  embryo  sac,  i. 

At/,  g,  h  is  \htpistil,  which  is  composed  of  the  enlarged 
basal  portion  (/),  known  as  the  ovary,  the  more  or  less 
slender  prolongation  of  this  (g),  called  the  style,  and  a  por- 
tion of  the  style  (//)  near  the  apex,  termed  the  stigma, 
which  is  usually  somewhat  rough  and  sticky  so  as  to  catch 
and  hold  the  pollen.  Sometimes  the  style  is  very  short, 
and  the  stigma  appears  to  rest  on  the  top  of  the  ovary. 

Within  the  ovary  and  growing  to  it  are  the  ovules  (one 
shown  aty  ),  which  are  destined  to  become  the  seed.  The 


1 66  Introduction  to  Botany. 

ovule  contains  a  large  cell,  or  spore  (z),  which  produces  the 
egg,  and  is  therefore  necessary  to  the  production  of  seed. 

The  flower  may  be  lacking  in  both  calyx  and  corolla,  but 
if  it  have  stamens  and  pistil,  or  only  pistil,  provided  pollen 
is  brought  to  it  from  some  other  flower  of  the  same  kind  of 
plant,  it  may  still  bear  seed.  For  this  reason  the  stamens 
and  pistil  are  called  the  essential  parts  of  the  flower. 

That  portion  of  the  flower  from  which  the  calyx,  corolla, 
stamens,  and  pistil  spring  is  called  the  receptacle  (a). 

120.  Process  of  Fertilization. — -In  order  that  the  fertili- 
zation of  the  egg  may  take  place,  the  sperm  from  the 
pollen  must  reach  the  egg  in  the  ovule,  which  in  most 
cases  is  entirely  shut  off  from  the  exterior  world  by  the 
walls  of  the  ovary.  We  can  see  that  in  this  case  it  would 
avail  little  for  the  sperm  to  be  motile  from  plant  to  plant, 
as  in  the  case  of  Oedogoniwn,  for  it  would  have  to  pass 
through  the  air,  instead  of  through  water,  and  would  be 
carried  rather  by  the  winds  than  by  its  own  motion.  The 
process  of  the  transference  of  the  sperm  has  therefore 
been  modified  to  meet  the  aerial  environment  The 
anthers  burst  open,  and  the  liberated  pollen  is  then  blown 
about  by  the  wind,  or  is  carried  from  flower  to  flower  by 
insects  which  are  seeking  nectar  or  pollen  for  food  for 
themselves  or  their  young;  or  in  some  cases  the  anthers 
may  touch  the  stigmas  and  transfer  to  them  their  pollen, 
or  the  pollen  may  drop  from  the  anthers  upon  the  stigmas ; 
while  in  water  plants  it  may  be  carried  to  its  destination  by 
means  of  movements  of  the  water. 

After  the  pollen  has  been  transferred  to  the  stigma  (as 
at  m,  Fig.  88)  it  imbibes  moisture  from  the  moist  and  sugary 
stigmatic  surface,  and  increases  in  size  so  that  finally  the 
inner  membrane  (represented  by  the  innermost  line  of 
the  pollen  case)  pushes  through  the  outer  coat  (thick,  and 


Flowers. 


i67 


shaded  with  diagonal  lines) 
either  through  thin  places  de- 
signed for  the  purpose,  or 
through  crevices  caused  by 
swelling  of  the  inner  parts,  and 
grows  forth  in  the  form  of  a 
slender  tube  (/).  This  pene- 
trates between  the  cells  of  the 
tissues  of  the  style,  from  which 
it  derives  nourishment,  until 
it  reaches  the  cavity  («)  of 
the  ovary,  in  which  the  ovule 
(/)  is  contained,  and  then  it 
seeks  the  opening  (micropyle) 
through  the  coats  of  the  ovule, 
and,  passing  through  this, 
reaches  the  spore  (s)  called 
the  embryo  sac,  in  which  the 
egg  (k)  is  borne.  Then  the 
pollen  tube  breaks  open,  and 
the  sperm  (n),  which  has  been 
passing  down  within  the  tube 
as  it  elongated,  fuses  with  the 
egg  (see  Fig.  89,  where  h  is 
the  egg  cell,  /,  pollen  tube,  and 
//  the  uniting  sperm  and  egg 
nuclei).  This  fusion  of  the  two 
sexual  elements  is  called  the 
fertilization  of  the  egg. 

The  egg  and  the  sperm  are 
both  protoplasts,  —  that  is,  they 
both  consist  of  plasma  mem- 
brane, cytoplasm,  nucleus,  and 


FIG.  88. 

Showing  the  descent  of  the  Pollen 
tube  and  its  entrance  into  the  Ovule. 
m,  pollen  grain  on  the  stigma;  /,  the 
pollen  tube ;  n,  the  sperm  cell  which 
has  descended  the  tube  and  is  ready 
to  penetrate  the  embryo  sac,  s,  and 
fuse  with  the  egg  cell,  k.  Below  k 
are  two  cells  termed  the  synergids  ; 
e,  two  nuclei  which  fuse  and  form 
the  secondary  nucleus  of  the  em- 
bryo sac,  from  the  division  of  which 
the  tissue  of  the  endosperm  arises ; 
g,  the  nucellus ;  /  antipodal  cells ; 
z,  outer,  and  yt  inner  coat  of  the 
ovule ;  u,  cavity  of  the  ovary. 


i68 


Introduction  to   Botany. 


plastids,  the  nucleus  making  up  by  far  the  greater  part  of 
the  sperm  protoplast,  while  the  egg  is  relatively  rich  in 
cytoplasm.  Here  we  have  evidence  that  the  nucleus  in 

particular  is  the  bearer 
of  the  inheritable  quali- 
ties, since  the  offspring 
may  inherit  more  of  the 
peculiarities  of  the  plant 
furnishing  the  sperm 
than  of  the  plant  bear- 
ing the  egg. 

121.  Result  of  Fertili- 
zation. —  After  the  egg 
has  been  fertilized  it 
forms  a  wall  about  it- 
self, and  begins  a  series 
of  cell  divisions  which 
result  in  the  formation 
of  the  embryo,  with 
which  we  have  already 
become  acquainted  in 
our  study  of  seeds.  At  the 'same  time,  within  the  embryo 
sac  other  cells  are  being  produced  which  become  gorged 
with  food  materials.  This  food-bearing  tissue  is  called  the 
endosperm.  The  reserve  food  remains  either  entirely  out- 
side of  the  embryo,  as  in  the  case  of  the  castor  bean,  or 
it  may  become  absorbed  by  the  cotyledons  about  as  fast 
as  it  is  produced,  as  illustrated  by  the  Lima  bean ;  or  it 
may  be  only  partly  absorbed  by  the  embryo,  as  in  Indian 
corn. 

The  fertilization  of  the  egg  stimulates  not  only  the 
growth  of  the  embryo  and  the  accumulation  of  reserve 
food,  but  it  also  incites  the  growth  of  the  ovule  as  a  whole 


FIG.  89. 

Showing  the  fusion  of  the  nuclei  of  the  Sperm 
and  of  the  Egg  cell..  /,  the  pollen  tube ;  h,  the 
egg  cell ;  u,  the  coalescing  of  sperm  and  egg 
nuclei  which  is  the  essential  process  of  the 
fertilization  of  the  egg. 


Flowers.  1 69 

and  the  further  development  of  the  ovary,  and,  in  some 
cases,  of  the  receptacle  and  calyx.  If  the  egg  is  not  fer- 
tilized, the  whole  flower  soon  drops  off ;  but  once  fertiliza- 
tion is  achieved,  the  ovary  persists  and  develops  into  the 
mature  fruit.  Evidently  there  is  here  a  transmission  of  a 
stimulus  from  the  fertilized  egg  to  all  parts  of  the  ovary 
and  even  to  other  structures  of  the  flower. 

122.  Time  required  for  Fertilization.  —  The  distance  trav- 
ersed by  the  pollen  tube  varies  from  one  to  a  few  milli-' 
meters  in  the  case  of  the  smaller  flowers  to  about  forty 
centimeters  through  the  long  styles  of  Indian  corn,  com- 
monly known  as  the  silk.     The  time  which  elapses  between 
the  deposition  of  the  pollen  on  the  stigma  and  the  fusion 
of  the  sperm  with  the  egg  may  therefore  vary  from  a  few 
hours  to  several  days.     In  the  case  of  the  pine,  for  other 
reasons,  the  interval  extends  through  an  entire  year. 

123.  Relative  Value  of  Asexual  and  Sexual  Reproduction. 
—  If  we  consider  the  relative  cost  to  the  plant  of  the 
asexual  and  the  sexual  methods  of  reproduction,  we  can 
see  that  the  sexual  method  is  much  the  more  expensive  in 
materials  and  energy.     The  calyx  and  corolla  are  costly 
contrivances,  and  the  production  of  nectar  and  aromatic 
substances  for  the  allurement  of  insects,  and  of  styles  and 
elaborate  stigmatic  surfaces,  has  been  at  the  cost  of  much 
valuable  material;  but,  added  to  this,  most  of  the  pollen 
does  not  reach  the  stigma  and  never  takes  part  in  fertiliza- 
tion, and  is  therefore  an  entire  loss. 

The  struggle  for  existence  among  plants  is  too  great  to 
permit  any  extravagance  that  does  not  bring  with  it  some 
amply  compensating  benefits  ;  and  we  might  therefore  con- 
clude that  the  expensive  and  elaborate  contrivances  which 
we  find  attending  the  sexual  method  result  in  some  great 
advantage.  It  will  perhaps  add  to  the  clearness  of  the 


i jo  Introduction  to  Botany. 

discussion  to  state  at  once  that  the  devices  of  flowers  are 
chiefly  for  the  purpose  of  securing  the  cooperation  of  two 
individuals  in  the  production  of  offspring,  and  that  the  off- 
spring thus  produced  are  stronger  and  better  equipped 
for  the  struggle  for  existence  than  those  which  arise  by 
the  division  of  a  single  individual. 

This  has  been  clearly  shown  by  experiments  by  Darwin, 
which  were  carried  out  through  a  period  of  many  years, 
and  in  which  a  large  number  of  species  was  employed. 
These  experiments  show  that  if  the  egg  is  continually  fer- 
tilized by  the  sperm  from  the  same  flower  (self  fertilization), 
or  from  another  flower  of  the  same  plant  (cross  fertiliza- 
tion in  a  narrow  sense),  through  a  number  of  generations, 
the  resulting  individuals  are  smaller  and  weaker,  and  pro- 
duce smaller  and  a  less  number  of  seeds  than  those  indi- 
viduals which  have  for  an  equal  number  of  generations 
resulted  from  the  fertilization  of  eggs  by  sperms  which 
have  been  brought  from  the  flowers  of  different  plants 
(cross  fertilization  in  a  more  exact  sense),  provided  the 
plants  taking  part  in  the  cross  fertilization  were  not  de- 
scended from  the  same  immediate  ancestors,  and  were 
therefore  not  closely  related. 

Darwin  concluded  from  his  experiments  "that  the  mere 
act  of  crossing  by  itself  does  no  good.  The  good  depends  on 
the  individuals  which  are  crossed  differing  slightly  in  con- 
stitution, owing  to  their  progenitors'  having  been  subjected 
during  several  generations  to  slightly  different  conditions, 
or  to  what  we  call  in  our  ignorance  spontaneous  variation." 

It  having  been  ascertained  that  cross  fertilization  as 
compared  with  self  fertilization  is  of  immense  advantage 
to  the  species,  the  manifold  devices  which  have  been 
evolved  to  prevent  self  fertilization  and  insure  cross  fertili- 
zation are  subjects  of  great  interest  and  meaning,  and  the 


Flowers.  171 

greater  value  of  the  sexual  as  compared  with  the  asexual 
method  of  reproduction  becomes  apparent. 

124.  Historical  Summary.  —  It  appears  from  the  writ- 
ings of  Aristotle  and  Theophrastus  (about  350  B.C.)  that 
only  vague  notions  were  entertained  at  that  time  about  the 
essential  nature  of  flowers.  It  was  a  common  practice  of 
the  palm  culturists  of  that  time  to  shake  the  branches  of 
the  staminate  trees  over  the  flowers  of  the  pistillate  trees 
(see  page  175  for  definition  of  staminate  and  pistillate),  in 
order  to- increase  the  production  of  fruit,  and  Theophrastus 
remarks  that  there  was  obviously  a  great  difference  in  the 
flowers ;  but  he  seems  not  to  have  attempted  to  find  out 
wherein  the  difference  consisted.  As  late  as  A.D.  60  Pliny 
writes,. in  speaking  of  the  date  palm,  that  the  pollen  dust 
is  the  material  of  fertilization,  and  that  naturalists  say  all 
trees  and  even  herbs  have  the  two  sexes,  but  knowledge  of 
the  subject  was  at  that  time  indefinite  and  conjectural.  It 
was  Camerarius  (1665-1721)  who  was  the  first  to  show  by 
definite  experiment  that  the  cooperation  of  the  pollen  is 
necessary  to  the  formation  of  an  embryo  within  the  ovule. 

Koelreuter  (1733-1806)  observed  the  nectar  and  noted 
the  aid  of  insects  in  pollination ;  and  he  produced  hybrids 
by  the  transference  of  the  pollen  of  one  species  to  the 
stigmas  of  the  flowers  of  another  species.  Conrad 
Sprengel  (1750-1816)  noted  that  cross  fertilization  between 
different  flowers  and  between  flowers  of  different  individ- 
uals was  of  common  occurrence  in  nature,  and  he  said  that, 
judging  from  the  construction  of  flowers,  nature  seemed  to 
have  intended  that  no  flowers  should  be  fertilized  by  their 
own  pollen ;  and  he  concluded  further  that  the  various 
peculiarities  of  structure  in  flowers  have  a  definite  relation 
to  insects  in  effecting  pollination.  While  Sprengel  dis- 
covered the  common  occurrence  of  cross  fertilization  by 


172  Introduction  to   Botany. 

means  of  wind,  insects,  etc.,  the  beneficial  effects  of  this 
process,  so  definitely  determined  by  the  experiments  of 
Darwin,  were  evidently  unsuspected  by  him. 

125.  SprengePs  Discoveries.  —  Sprengel's  book,  entitled 
"  The  Discovered  Secret  of  Nature  in  the  Structure  and 
Fertilization  of  Flowers  "  (Berlin,  1793),  is  of  great  inter- 
est to  the  student  of  botany,  not  only  because  it  contains 
an  exposition  of  many  important  discoveries,  but  also  be- 
cause it  reveals  an  inquiring  and  unprejudiced  mind,  capa- 
ble of  placing  facts  in  their  true  relationships,  and  of 
understanding  their  meaning.  A  few  paragraphs  from 
Sprengel's  book  are  here  given  as  an  illustration  of  his 
method  of  reasoning. 

"While  in  the  summer  of  1787  I  was  attentively  examin- 
ing the  flower  of  Geranium  sylvatictim,  I  found  that  the 
lowest  part  of  its  petals  was  provided  on  the  inside  and 
on  the  two  borders  with  fine  and  delicate  hairs.  Persuaded 
that  the  wise  Author  of  nature  has  not  created  even  a 
single  hair  without  a  definite  object,  I  considered  what 
purpose  these  hairs  might  possibly  serve.  And  in  this 
it  soon  occurred  to  me  that  if  one  assume  that  the  five 
drops  of  nectar,  which  are  secreted  by  the  same  number  of 
glands,  are  set  aside  for  the  food  of  certain  insects,  one 
would  then  not  find  it  improbable  that  provision  should  be 
made  to  preserve  this  nectar  from  injury  by  rains,  and  that 
these  hairs  had  been  placed  there  for  this  purpose.  .  .  . 

"Each  drop  of  nectar  sits  upon  its  gland  immediately 
under  the  hairs  which  occur  on  the  borders  of  the  two 
adjacent  petals.  Since  the  flower  stands  upright  and  is 
rather  large,  raindrops  necessarily  fall  into  it  when  it  rains. 
But  none  of  the  falling  raindrops  can  reach  a  droplet  of 
nectar  and  mix  with  it,  since  it  is  held  back  by  the  hairs 
which  occur  over  the  droplet  of  nectar,  just  as  a  drop  of 


Flowers.  173 

sweat  which  has  run  down  a  man's  forehead  is  caught  by 
the  eyebrow  and  eyelashes,  and  kept  from  entering  the  eye. 
An  insect,  on  the  contrary,  is  not  in  the  least  hindered  by 
these  hairs  from  getting  at  the  droplet  of  nectar. 

"  I  then  investigated  other  flowers,  and  found  that  vari- 
ous sorts  had  something  in  their  structure  which  seemed  to 
serve  this  same  purpose.  The  longer  I  pursued  this  in- 
vestigation, the  more  I  perceived  that  those  flowers  which 
contain  nectar  are  so  constructed  that  insects  indeed  can 
get  at  it  very  easily,  but  that  the  rain  cannot  spoil  it.  I 
therefore  concluded  that  the  nectar  of  these  flowers  is 
secreted,  at  least  principally,  for  the  sake  of  insects,  and 
in  order  that  they  may  enjoy  it  pure  and  unspoiled,  it  is 
protected  against  the  rain. 

"  In  the  following  summer  I  investigated  the  forget-me- 
not  (Myosotis  palustris}.  I  found  that  this  flower  not  only 
has  nectar,  but  also  that  the  nectar  is  fully  protected 
against  the  rain.  But  at  the  same  time  I  was  struck  by 
the  yellow  ring  which  surrounds  the  mouth  of  the  corolla 
tube,  and  contrasts  so  beautifully  with  the  sky-blue  limb  of 
the  corolla.  Might  possibly,  thought  I,  this  circumstance 
also  relate  to  insects  ?  Might  nature  perhaps  have  colored 
this  ring  for  the  special  purpose  of  showing  insects  the 
way  to  the  nectar  receptacle  ?  With  this  hypothesis  in 
mind  I  examined  other  flowers  and  found  that  most  of  them 
corroborated  it.  For  I  saw  that  those  flowers  whose 
corolla  is  colored  in  any  way  differently  from  the  general 
coloring  always  have  these  spots,  figures,  lines,  or  splashes 
of  distinct  color  where  the  entrance  to  the  nectar  receptacle 
occurs.  From  the  part  I  conceived  the  whole.  If,  thought 
I,  the  corolla  is  colored  differently  in  any  place  especially 
for  the  sake  of  insects,  its  whole  coloring  must  also  be  for 
their  sake  ;  and  if  any  distinct  color  of  a  part  of  a  corolla 


Introduction  to  Botany. 


is  for  the  purpose  that  an  insect  which  has  alighted  on  the 
flower  may  easily  find  the  right  way  to  the  nectar,  so  the 
color  of  the  corolla  as  a  whole  is  for  the  purpose  that 
the  flowers  possessed  of  such  a  corolla  may  be  recognized 


(Mi t deck (e  Gelieiiiiiiils 


CHRISTIAN  KONRAD  SPRENGEIV 


c^-  Vc  c-^V^i ii(j  ^>  -^ 

Vat'Aveo^«lem  ;elteru 


ES^ 


.Mu^:. 

_.¥>;.,._.. 


i»l| 


XIV  •»>  .Nffl 


FIG.  90. 

Reduced  facsimile  of  the  title-page  of  Sprengel's  book,  "  The  Discovered  Secret  of 
Nature  in  the  Structure  and  Fertilization  of  Flowers." 

from  afar  as  receptacles  of  nectar  by  insects  which  are  fly- 
ing about  in  quest  of  food. 


Flowers.  175 

"While  in  the  summer  of  1787  I  was  studying  some 
species  of  Iris  I  soon  found  .  .  .  that  the  nectar  is  fully 
protected  from  the  rain,  and  that  there  are  specially 
colored  places  which  lead  the  insects  to  the  nectar.  But  I 
found  still  more,  namely,  that  the  flowers  cannot  possibly 
be  fertilized  in  any  other  way  than  by  means  of  insects, 
and  in  fact  by  insects  of  considerable  size.  .  .  .  My  in- 
vestigations ever  more  and  more  convinced  me  that  many, 
indeed  perhaps  all,  flowers  which  have  nectar  are  fertilized 
by  the  insects  which  obtain  food  from  this  nectar." 

Figure  90  is  a  reduced  facsimile  of  the  title-page  of 
Sprengel's  book;  the  various  flowers  of  the  border -give 
some  idea  of  the  variety  of  forms  worked  out  by  him. 

126.  Devices  for  Cross  Fertilization.  —  The  ability  of 
plants  to  adapt  their  members,  by  modifications  of  form  and 
structure,  to  various  conditions  and  ends,  is  perhaps  best 
shown  in  the  construction  and  behavior  of  their  flowers. 
The  end  which  most  flowers  seek  to  attain,  as  long  since 
pointed  out  by  Sprengel,  is  cross  fertilization,  and  the 
agents  to  which  they  have  to  adapt  themselves  are  wind, 
insects  and  other  animals,  and  water.  In  order  that  cross 
fertilization  may  be  achieved  it  is  of  paramount  importance 
that  self  fertilization  should  be  prevented,  and  we  accord 
ingly  find  special  devices  having  this  end  in  view. 

The  chief  of  these  devices  are  as  follows :  (i)  Only  one 
sex  is  represented  in  each  flower,  but  both  sexes  occur  on 
the  same  plant.  The  flowers  which  contains  the  stamens 
are  called  staminate,  while  those  which  contain  the  pistils 
are  called  pistillate ;  the  flowers  in  this  case  are  called 
monoecious  (see  Glossary  for  derivation  of  terms).  (2)  The 
pistillate  flowers  only  are  borne  on  one  plant,  while  the 
staminate  flowers  are  borne  on  another  plant ;  such  flowers 
are  called  di&cious.  (3)  The  flowers  contain  both  sexes, 


176 


Introduction  to   Botany. 


but  (a)  the  pistils  and  anthers  are  not  mature  at  the  same 
time.  Thus  the  stigmas  may  be  ready  to  receive  the  pollen, 
but  the  anthers  are  not  ready  to  break  open  and  discharge 

the  pollen,  or  vice  versa ;  such 
flowers  are  called  dichogamous. 
If  the  stamens  mature  first,  the 
flowers  are  proterandrous ;  if 
the  pistils  mature  first,  they 
are  proterogynous.  (b)  The 
stamens  and  pistils  may  differ 
greatly  in  length,  so  that  the 
pollen  would  not  be  apt  to  at- 
tain to  the  stigmas  of  the  same 
flower.  Flowers  of  this  kind 
are  called  dimorphic  if  the 
stamens  and  pistils  are  each 
of  two  different  lengths,  or 
trimorphic  if  of  three  different 
lengths,  (c)  The  relative  posi- 
tion of  stamens  and  pistils 
may  in  other  ways  be  such  as 
to  keep  the  pollen  from  the 
stigma,  or  other  parts  of  the 
flower  may  intervene  between 
them. 

The  devices  to  prevent  self 
fertilization  are  also  in  the 
interest  of  cross  fertilization.  If  the  flowers  are  dioecious, 
insects  in  going  from  one  plant  to  another  are  quite  certain 
to  carry  pollen  from  the  staminate  flowers  to  the  stigmas 
of  the  pistillate,  or  the  wind  may  accomplish  the  same 
thing.  An  insect  in  visiting  dichogamous  flowers  would, 
in  the  case  of  proterandry,  carry  pollen  from  the  stamens  of 


FIG.  91. 

Cross  pollination  of  Primula,  a  di- 
morphic flower.  In  A  a  bee  is 
gathering  nectar  at  the  base  of  the 
pistil  while  its  head  is  in  contact 
with  the  anthers  inserted  in  the 
throat  of  the  corolla.  In  gathering 
nectar  from  the  long-styled  flower, 
B,  the  pollen  on  its  head  will  be 
deposited  on  the  stigma,  and  at  the 
same  time  pollen  from  the  low 
stamens  will  be  brushed  off  on  its 
proboscis  at  the  right  height  to  be 
transferred  to  the  stigma  of  a  short- 
styled  flower  as  in  A.  —  WISE. 


Flowers. 


177 


the  younger  flowers  to  the  stigmas  of  the  older,  or  vice  versa 
in  case  of  proterogyny.  In  dimorphic  flowers  the  pollen 
from  short  anthers  would  quite  certainly  be  deposited  by 
insects  on  the  stigmas  of  the  short  pistils,  as  in  going 
from  B  to  A,  Fig.  91. 

Adaptations  for  cross  fertilization  are  perhaps  best  seen 
in  the  various  adjustments  of  flowers  to  the  agents  which 
are  to  transport  the 
pollen  and  deposit  it 
on  the  stigma.  These 
agents,  as  has  been 
stated,  are  wind,  in- 
sects and  other  ani- 
mals, and  water. 

127.  Adaptation  to 
Wind.  —  Those  flow- 
ers which  depend 
upon  the  wind  for 
transporting  the  pol- 
len are  characterized 
by  protruding  stamens  and  a  relatively  large  expanse  of 
stigmatic  surface ;  this  is  well  shown  by  Indian  corn, 
whose  staminate  flowers  surmount  the  plant  and  send  forth 
numerous  pendent  stamens  which  offer  their  pollen  to  the 
wind.  The  long  silken  styles  which  protrude  beyond  the 
husks  of  the  pistillate  inflorescence,  or  ear,  present  a 
large  surface  for  arresting  the  pollen  as  it  is  being  carried 
about  by  winds. 

The  pines,  poplars,  and  willows  illustrate  the  same 
thing  in  somewhat  different  ways.  The  pollen  of  the  pine 
is  borne  in  great  abundance  in  the  staminate  catkins  (see 
Fig.  92),  and  each  grain  is  provided  with  two  balloon-like 
expansions  containing  air,  which  contribute  to  its  lightness 


FIG.  92. 

Staminate  catkin  of  the  Pine. 


178 


Introduction  to   Botany. 


and  sailing  qualities.  The  pistillate  inflorescence  is  in 
the  form  of  a  cone  (Fig.  93,  a)  whose  scales  are  broadly 
expanded  and  collect  the  pollen  as  it  settles  down  upon 

them,  directing  it  downward 
to  their  axils,  where  it  comes 
in  close  proximity  to  the 
micropyles  of  the  naked 
ovules  (see  Fig.  94). 

The  staminate  catkins  of 
the  poplars  are  shaken  and 
emptied  by  the  wind,  while 
the  branched  and  widely 
spreading  stigmas  of  the 
pistillate  flowers,  occurring 
on  a  different  tree,  catch 
and  hold  the  pollen  which 
is  wafted  to  them. 

It  is  characteristic  of 
flowers  which  depend  on 
the  wind  that  they  are  either 
monoecious  or  dioecious.  It 
is  plain  that  this  mode  of 
pollen  transference  is  ex- 


FIG.  93. 

Pistillate  inflorescence  of  the  pine.    At  a, 
young  cone  of  the  current  spring  ready 
to  receive  pollen  ;£,  cone  which  the  pre-    pensive,    SHICC    ITiOSt    of    the 
vious  spring  was  like  a;   c,  cone  one 

year  older  than  b ;  here  the  scales  have    pollen  must  be  lost  in   tran- 
spread  apart  and  the  seeds  have  dropped 
out. 


sit.  There  is  some  com- 
pensation, however,  in  the 
fact  that  allurements  for  insects  in  the  form  of  brightly 
colored  corollas,  nectar,  and  fragrant  odors  are  not  neces- 
sary, and  are  accordingly  not  produced. 

128.  Cross  Pollination  by  Water.  —  In  the  case  of  flower- 
ing plants  which  are  entirely  submerged  in  water,  the  pollen 
frequently  has  the  same  specific  gravity  as  the  water,  and 


Flowers. 


179 


FIG.  94. 

boat-shaped  Fruiting  Scale  or  Carpel  from  a 
young  Pine  Cone.  A,  seen  from 
the  front,  showing  two  ovules; 
B,  diagram  of  a  longitudinal 
section  of  A,  seen  from  the  side. 
m,  micropyle ;  n,  embryo  sac. 
A,  after  BESSEY ;  B,  after  CALD- 
WELL. 


is   readily  dispersed  from  flower  to  flower  at  any  depth. 

In  the  case  of  Vallisneria  spiralis 

(see    Figs.    95-96)   the   pistillate 

flowers    rise    to   the    surface    on 

slender    stems.      The    staminate 

flowers,  which  are  formed  under 

the  water,  break  loose  from  their 

stems  and  float  on  the  surface,  the 

calyx   consisting   of 

sepals   which  buoy  the    stamens 

above  the  surface,  and  allow  them 

to  float  high  and  dry.     The  sta- 
mens bend  outward  beyond  the  rim 

of  the  calyx,  and  when  the  stami- 
nate and  pistillate  flowers 
are  brought  together  by  the 
wind  or  currents  of  water, 
the  anthers  come  in  contact 
with  the  stigmas  and  effect 
their  pollination.  The  stem 
which  bears  the  pistillate 
flowers  then  coils  itself  spi- 
rally and  draws  the  flower 
to  the  bottom  of  the  water, 
where  the  seeds  may  ma- 
ture undisturbed. 

129.   Adaptations  to   In- 
sects. —  The  most  wonder- 
FIG.  95.  f  ul  modifications  of  flowers 

Vallisneria  spiralis.     The  plant  on  the  left  are    found    in    those    f OrniS 
bears  staminate  flowers  which  are  break- 

ing  away  and  rising  to  the  surface.     The  which  are  adapted  to  CrOSS 

plant  on  the  right  bears  a  pistillate  flower  pollination  by  means  of  in- 
rising  on  a  long  stem  to  the  surface. — 

After  KEENER.  sects.     These  have  had  to 


i8o 


Introduction  to  Botany. 


provide  for  the  allurement  of  insects  by  offering  them  nectar 
and  pollen  for  food,  and  for  attracting  their  attention  by 
means  of  odors  and  bright  colors  ;  and  at  the  same  time  they 

have  had  so  to  con- 
struct and  arrange 
their  parts  that  in- 
sects in  securing  food 
would  necessarily 
carry  the  pollen  from 
one  flower  to  the 
stigma  of  another. 

130.  Allurement 
by  Pollen.  —  Some 
flowers  secrete  no 


FIG.  96. 


Pistillate  and  staminate  flowers  of  Vallisneria  spiralis. 

On  the  right  a  staminate  flower  has  floated  against  nectar  but  offer  an 
the  pistillate  flower  and  an  anther  is  touching  one  abundance  of  pollen, 
of  the  stigmas.  After  KERNER. 

Roses,  Anemones, 

and  poppies  are  of  this  sort.  Flowers  of  this  kind  are 
more  or  less  erect  so  that  the  pollen  may  not  fall  out,  and 
the  stamens  are  usually  numerous.  Insects  which  feed  on 
the  pollen  of  such  flowers  are  certain  to  get  their  bodies 
dusted  over,  and  in  this  way  they  carry  the  pollen  from 
flower  to  flower. 

131.  Allurement  by  Nectar.  —  Nectar  is  the  most  com- 
mon and  most  important  allurement  for  insects.  It  is  a 
more  or  less  watery  solution  of  sugar,  and  of  certain  salts 
and  aromatic  substances,  secreted  by  a  special  tissue  known 
as  the  nectary,  and  expelled  at  the  surface  by  transfusion 
through  the  epidermis,  by  breaking  down  of  the  tissues,  or 
through  a  special  opening  of  the  nature  of  a  stoma.  The 
nectar  either  remains  clinging  to  the  surface  of  the  nectary 
or  it  gathers  in  large  drops  and  falls  into  a  nectar  recepta- 
cle provided  for  it,  as  in  the  case  of  -violets,  where  horn- 


Flowers.  181 

like  outgrowths  from  the  two  lower  stamens  secrete  the 
nectar  and  pour  it  into  a  cup  formed  by  the  base  of  the 
lower  petal. 

The  nectaries  may  occur  on  any  part  of  the  flower,  but 
they  are  most  frequently  found  at  the  bases  of  the  stamens, 
petals,  and  ovaries,  and  rarely  on  the  calyx.  In  the  plum 
and  peach  they  form  a  thick  inner  lining  of  the  cup-shaped 
receptacle.  In  Nasturtiums  the  nectar  is  secreted  in  a 
long  spur  from  the  calyx. 

Some  flowers  of  simple  construction  expose  their  nectar 
freely  to  all  sorts  of  insects,  but  others  conceal  it  in  various 
ways  so  that  it  is  accessible  only  to  insects  of  certain  kinds. 
A  frequent  device  is  to  have  some  parts  of  the  corolla  close 
over  the  way  to  the  nectar  so  that  small  insects  which 
would  not  assist  in  cross  pollination  are  excluded,  and  only 
those  which  are  strong  enough  to  push  aside  the  barrier 
or  have  proboscides  of  proper  construction  to  thrust  past 
it  can  obtain  the  nectar  and  accomplish  the  transference 
of  the  pollen. 

The  student  is  quite  certain  to  find  that  irregularities  and 
complexities  of  floral  structure  are  in  the  interest  of  the 
protection  of  the  nectar  or  pollen  and  the  transference 
of  the  latter  from  one  flower  to  another. 

132.  Color  and  Fragrance.  —  As  Sprengel  pointed  out, 
flowers  not  only  provide  food  for  insects,  but  they  also 
furnish  advertisements  in  the  way  of  brilliant  colors  and 
agreeable  odors  to  notify  insects  from  afar  where  food 
awaits  them,  and  lines,  spots,  etc.,  of  special  color  to  show 
insects  coming  to  the  flowers  the  direct  way  to  the  nectar. 
It  appears  from  various  experiments  that  the  odor  is  most 
effective  in  attracting  insects  from  a  considerable  distance, 
and  that  on  the  nearer  approach  of  the  insect  the  color  be- 
comes an  important  guide.  There  seems  to  be  no  doubt 


182 


Introduction  to  Botany. 


that  insects  have  a  keener  sense  of  smell  than  our  own, 
and  are  attracted  by  the  odors  of  flowers  which  we  cannot 
detect;  but  their  vision,  except  at  short  distances,  is  not 
sharp.  They,  however,  appear  to  appreciate  differences  in 
color  at  a  distance  where  the  forms  of  objects  are  still 
indistinct  to  them. 

133.  Sense  of  Smell  in  Insects.  —  The  nerves  of  insects 
that  are  sensitive  to  odors  ramify  and  come  to  the  surface 

in  the  antennae, 
which  are  under- 
stood to  be  their 
organs  of  smell 
(Fig.  97).  That  the 
sense  of  smell  may 
be  very  keen  in  in- 
sects is  shown  by 
the  fact  that  they 
can  go  unerringly 

Photomicrograph  of  the  head  of  a  Sphinx  Moth,  X  3, 

showing  the  antennae  in  which  are  located  the  nerves  to       mCOnSplCUOUS 

of  smell,  and  the  large  compound  eye.    The  long  pro-  and        Concealed 

boscis  is  coiled  like  a  watch  spring  out  of  sight  be-  ., 

neath  the  eye.  flowers  which  to  US 

may  be  scentless. 

134.  Sense  of  Sight  in  Insects.  —  The  eyes  of  insects  are 
compound,  —  that   is,    they   are   composed    of    numerous 
smaller  eyes  all  grown  together,  and  in  communication  with 
the  same  optic  nerve,  and  therefore  really  constituting  one 
organ      The  number  of  single  eyes  or  facets  may  amount 
to  twenty-five  thousand.     The  end  of  each  facet  has  the 
appearance  of  a  convex  hexagonal  disk.     Figure  98  repre- 
sents  a  longitudinal  section  of   the  eye  of   a  cockroach 
which  may  be  taken  as  a  type  of  the  compound  eye.     At 
/  is  a  lens-like  body,  clear  as  glass,  whose  outer  face  is 
at  the  surface  of  the  eye.     The  light  passing  through  this 


FIG.  97. 


Flowers. 


183 


next  traverses  the  crystal  cone  ky  which  is  also  a  trans- 
parent lens.  The  nerve  tissue  /,  m,  and  ;/,  is  in  immediate 
communication  with  these  lenses,  and  transmits  the  light 
stimuli  to  the  main  optic  nerve,  and 
thence  to  the  nerve  ganglia  which 
represent  the  brain. 

The  compound  eye  of  an  insect 
does  not  form  an  image  in  the  same 
manner  as  does  the  human  eye,  in 
which  divergent  rays  of  light  from 
any  point  are  brought  to  a  focus  on 
the  retina,  and  a  relatively  bright 
inverted  image  is  formed.  Insects 
can,  therefore,  not  see  as  well  as  we 
can.  This  appears  to  be  borne  out 
by  the  action  of  insects,  which  do 
not  seem  to  appreciate  the  forms  of 
objects  well  until  they  are  quite  near 
to  them.  FIG98 

Since  the   main  object   of   insects'     Diagram  of  the  compound  Eye 


of  an  Insect.  A,  a  surface 
view  of  some  of  the  simple 
eyes  united  to  form  a  com- 
pound eye.  B,  a  longitu- 
dinal diagram  of  three 
simple  eyes.  See  text.  The 
image  formed  is  said  to  be 
a  mosaic,  each  simple  eye 
contributing  a  distinct  por- 
tion. After  LUBBOCK. 


visiting  flowers  is  that  of  obtaining 
food  for  themselves  or  their  young, 
their  relations  to  flowers  will  be 
better  appreciated  when  the  con- 
struction of  their  food-gathering  ap- 
paratus is  understood;  and  for  this 
purpose  the  bees  and  butterflies  will 
be  chosen  for  examples,  because  they  represent  two  kinds 
of  insects  which  are  most  important  to  flowers. 

135.  Relation  of  Butterflies  to  Flowers.  —  Butterflies  sip 
the  nectar  only,  and  do  not  make  use  of  the  pollen ;  al- 
though in  getting  the  nectar  they  incidentally  transfer 
pollen  from  flower  to  flower.  They  do  not  carry  away 


184 


Introduction  to  Botany. 


and  store  nectar  for  themselves  or  their  young,  but  take 
only  what  they  immediately  desire  for  food.  They  do  not, 
on  the  whole,  seem  to  require  much  food  in  the  imago  or 
butterfly  state  (the  student  will  remember  that  in  the  first 

stage  of  their  existence 
after  hatching  from  the  egg 
they  are  caterpillars),  al- 
though they  are  sometimes 
so  eager  for  the  nectar  that 
they  may  be  caught  in  the 
hand  while  obtaining  it. 

The  organ  by  means  of 
which  the  nectar  is  secured 
is  known  as  the  proboscis ; 
it  is  long  and  slender,  and 
contains  muscles,  nerves, 
and  air  tubes,  and  a  cavity 
for  sucking  up  liquids  (Fig. 
99,  A  and  B).  When  the 
proboscis  is  not  in  use,  it  is 
tightly  coiled  like  a  watch 
spring,  and  tucked  away  in 

A,  longitudinal  diagram  of  the  head  of  a 

Butterfly,   o,  s,  p,  g,  muscles  operating   small    space    beneath    the 

£  £^ST5^"«S±£:  head  (coraPare  Fiss-  97 

cavity ;  t,  oesophagus ;  B,  cross  diagram  and     104).        The     proboscis 
of  butterfly's  proboscis.      The   central  •  n      •i-i  j     •  i 
cavity  is  for  suction  and  the  lateral  cavi-  1S    vei7    flexible    and    IS    ad- 
ties  carry  muscles,  nerves,  and  air  tubes,  mir  ably     Constructed     for 
After  BURGESS.                                                   i  •         r                       11- 

probing  for  concealed  nec- 
tar or  for  reaching  to  the  bottom  of  flowers  with  long  tubes, 
such  as  those  of  the  morning  glory,  petunia,  etc.  Flowers 
which  are  especially  adapted  to  butterflies  and  moths  (the 
difference  between  butterflies  and  moths  being  inconsequen- 
tial) are  so  constructed  that  the  proboscis  comes  in  contact 


Flowers. 


i85 


with  both  anthers  and  stigmas,  so  that  the  pollen  is  quite 
certain  to  be  transferred  from  one  flower  to  the  stigmas 
of  another. 

136.  Relation  of  Bees  to  Flowers.  —  Bees  gather  and 
store  up  both  nectar  and  pollen  for  themselves  and  their 
young,  and  are  more  indefatigable 
than  all  other  insects  in  their  visits 
to  flowers.  Their  mouth  parts  are 
so  constructed  that  they  can  transfer 
pellets  of  pollen,  by  means  of  their 
mandibles,  directly  to  the  so-called 
mouth  or  opening  into  the  pharynx, 
whence  it  passes  through  the 
oesophagus  into  the  stomach ;  or 
they  can  adjust  an  elongated  suction 
apparatus  to  the  mouth  opening,  and 
by  means  of  it  suck  up  nectar  from 

more  or  less  concealed  nectaries. 

% 

Since  bees  depend  almost  entirely  The  head  and  mouth  parts  of 
upon  flowers  for  their  food,  and  are 
at  the  same  time  of  inestimable 
value  to  plants  in  accomplishing 
cross  pollination,  it  may  be  taken 
for  granted  that  the  structures  of 
bees,  and  of  flowers  visited  by  them,  have  been  evolved 
side  by  side,  and  have  influenced  each  other  by  their  inter- 
dependence. The  mouth  parts  of  the  bee  (Fig.  100)  are 
used,  not  only  for  collecting  food,  but  also  in  the  construc- 
tion of  the  comb,  and  in  other  manifold  duties  pertaining 
to  the  care  of  the  young. 

The  bee  flies  from  flower  to  flower  until  the  honey 
stomach  (see  Fig.  101)  is  extended  to  about  T3g  of  an  inch  in 
length  and  T2g-  of  an  inch  in  breadth ;  it  then  flies  to  the  hive, 


ble ;  g ,  flap  over  the  mouth  ; 
ntx,  maxilla;  //,  labial  pal- 
pus; /,  tongue  or  ligula 
with  button-like  extremity  b. 
After  CHESHIRE. 


i86 


Introduction  to  Botany. 


and  by  a  contraction  of  the  honey  stomach  empties  its  load 
of  honey  into  the  cells  of  the  comb  ;  then,  urged  by  an 

irresistible  instinct,  it 
flies  forth  to  repeat  the 
process  again  and  again 
until  darkness  sets  in. 
It  can  be  seen  at  once 
that  the  industry  of  the 
bee  places  it  in  the  fore- 
front of  insects  useful 
in  the  cross  pollination 
of  flowers. 
FIG-  I01-  As  has  been  said,  bees 

Longitudinal  diagram  of  the  head  and  a  part  ajso  coHect  pollen  as  an 

of  the  body  of  the  honey  bee."  g,  the  flap  .  r 

over    the    mouth     opening;     mx,    maxilla;  important  food  for  them- 

//,  labial  palpi;  /.the  tongue;  o,  the  oesoph-  selves   an(J   their   VOUng;. 
agus;    s,  honey  stomach.      When    at  rest  +  ° 

the  maxillae,  tongue,  and   labial  palpi  are  Some   pollen  may  be  in- 

AffefcHaEtHiaREindiCated  by  the  dottedline'  cidentally  swallowed 

with     the     nectar,     but 

most  of  it  is  deftly  transferred  to  the  hind  legs,  where  it 
is  sometimes  heaped  up  in  large  masses,  having  been 
rendered  adhesive,  if 
necessary,  by  being 
mixed  with  nectar. 
Figure  102  is  a  photo- 
micrograph of  two  legs 
of  a  honey  bee,  one 
loaded  with  pollen  and 
the  other  empty.  Some 
other  bees,  notably  the 
green  bees  which  fre- 

Photomicrograph  of  two  posterior  legs  of  Honey 
Bees,  without  pollen  on  the  right,  and  with  a 
load  of  pollen  on  the  left,  x  3. 


FIG.  102. 


quent  the  yellow  pond 
lilies  at  early  morning, 


Flowers.  187 

have  long  curved  hairs  on  the  hind  legs  which  serve  as 
a  sort  of  basket  for  the  pollen,  as  shown  in  Fig.  103,  a 
and  b. 

Having  now  become  somewhat  acquainted  with  the 
equipment  of  butterflies  and  bees  for  dealing  with  flowers, 
it  will  be  well  to  consider  a  few  special  cases  showing 
how  the  need  of  the  insect  for  food  and  of  the  flower 
for  cross  pollination  are  mutually  satisfied. 

137.  Cross  Pollina- 
tion of  Datura.  —  Many 
flowers  possess  long 
tubes  at  the  bottom  of 
which  the  nectar  is 
stored ;  such  flowers 
usually  have  the  way  to 
the  nectar  obstructed 
by  a  constriction  of 

the   tube,  or  by   out-  FIG.  193. 

growths  in  the  form  of    A<  les  of  a  wild  bee  with  hairs  servins  as  baskets 

5    f  for  the  collection  of  pollen ;  B,  the  same  laden 

hairs,  etc.,  SO  that  Only         whh  pollen.    Photomicrograph  X  4. 

those    insects    having 

long  proboscides  can  reach  it.  The  common  jimson-weed 
(Datura  stramonium)  is  an  excellent  illustration  of  this. 
The  corolla  is  about  five  centimeters  long,  and  the  cavity 
of  the  tube  is  nearly  closed  at  about  the  middle  of  its 
length  by  the  insertion  of  the  filaments  there.  When  the 
flower  opens  in  the  evening,  it  emits  a  strong  musky  odor, 
and  a  large  drop  of  nectar  is  already  present  in  the 
bottom  of  the  tube ;  FO  that  large  sphinx  moths,  leaving 
the  places  of  seclusion  occupied  by  them  during  the  day, 
are  attracted  by  the  strong  odor  and  white  color  of  the 
flowers. 

Flying  swiftly  from  flower  to  flower,  the  moth  thrusts 


1 88  Introduction  to  Botany. 

its  long  proboscis  to  the  bottom  of  the  tube  and  secures 
the  nectar ;  and  while  it  is  tarrying  briefly  at  each  flower, 
keeping  itself  poised  by  the  swift  vibration  of  its  wings,  it 
is  pretty  certain  to  touch  with  its  proboscis  both  anthers 
and  stigmas,  which  stand  close  together  at  about  the  same 
height  near  the  mouth  of  the  corolla.  Both  cross  and  self 


FIG.  104. 

Sphinx  moth  and  flower  of  Datura  stramonium,  posed  to  show  the  relative  lengths 
of  the  flower  and  of  the  moth's  proboscis.    Reduced  rather  more  than  one-half. 

pollination  might  be  brought  about  in  this  way,  but,  as 
Darwin  has  shown,  the  foreign  pollen  would  probably 
possess  the  greater  potency,  and  cross  fertilization  would 
be  apt  to  result.  Figure  104  is  a  photograph  of  a  sphinx 
moth  and  Datura  flower,  posed  to  show  the  relative  lengths 
of  the  moth's  proboscis  and  the  corolla  tube. 

138.  Cross  Pollination  of  Sal  via.  —  In  the  Salvias,  or 
sages,  we  find  several  contrivances  working  together  for 
a  common  end.  The  corolla  is  tubular  below  and  two- 
lipped  above,  the  lower  lip  serving  as  an  alighting  place 
for  bees,  and  the  upper  forming  a  protective  covering  for 
the  stamens  and  style.  There  are  two  stamens  of  peculiar 
construction  set  one  on  either  side  of  the  mouth  of  the 


Flowers.  189 

corolla  (see  Fig.  105).  The  filament  (/)  is  very  short  and 
bears  a  two-armed  connective  (cc),  the  upper  arm  being 
long  and  thread-like  and  supporting  a  pollen-bearing  anther, 
while  the  lower  arm  is  short,  spatulate,  and  sterile.  By 
pressure  on  the  lower  arm  the  upper  arm  may  be  rotated 


FIG.  105. 

Pollination  of  Salvia  glutinosa.  i,  a  stamen.  The  upright  column  to  the  left  of/ 
is  the  filament,  c,  c,  the  connective,  anther  bearing  above  and  sterile  below. 
2  and  3,  longitudinal  diagrams  of  a  young  flower,  showing  the  anther  in  its 
natural  position  in  2,  and  pushed  down  by  a  bee  by  pressing  on  the  lower  part 
of  the  connective,  in  3.  4,  a  bee  visiting  a  younger  flower ;  the  anthers  pushed 
down  upon  its  back.  5,  a  bee  visiting  an  older  flower;  the  style  having  become 
elongated  and  pendent  touches  the  bee's  back.  After  K.ERNER. 

downward,  the  short  filament  acting  as  a  fulcrum.  When 
a  bee  which  has  alighted  on  the  lower  lip  attempts  to  thrust 
its  suction  apparatus  into  the  tube  of  the  corolla,  its  head 
presses  against  the  lower  arm,  and  the  two  anthers  are 
rocked  forward  until  they  press  against  the  bee's  body 
and  discharge  pollen  upon  it  (3  and  4).  In  the  younger 
flowers  the  styles  remain  close  under  the  upper  lip  (dia- 
grams 2  and  3),  but'  as  the  flowers  get  older  the  styles 
bend  down  so  that  visiting  bees  would  necessarily  rub 
their  backs  against  the  stigmas  (5).  In  this  way  the 


190 


Introduction  to   Botany. 


bees   transfer   pollen   from   the    younger   flowers    to   the 

stigmas  of  the  older  (4  and  5). 

139.  Cross  Pollination  of  Or- 
chids. —  In  orchids  we  find  so'me 
of  the  most  wonderful  modifica- 
tions of  the  parts  of  the  flower 
to  secure  cross  pollination.  Fig- 
ure 1 06  represents,  in  part,  the 
construction  of  the  flower  of 
Catasetum  tridentatum,  a  South 
American  orchid.  In  this  flower, 
as  in  orchids  in  general,  there 
are  three  colored  sepals  and  the 
same  number  of  colored  petals, 
one  of  the  petals  serving  as  a 
landing  place  for  insects,  and 
being  prolonged  into  a  spur  be- 
low for  the  conservation  of  the 
nectar.  The  irregular  central 
body  c,  known  as  the  column,  is 

A,    longitudinal    diagrams    of    the    composed  of  the  pistil  Confluent 
flower  of  Catasetum  tridentatum.        •,•!       ,1  •        i  T^, 

,,  the  column;    h,  the   sensitive    Wlth     the     Slngle     Stamen.       The 

spur; /,  poiiinium;  d,  viscid  disk,  upper  part  of  the  column  bears 

B,  projection  of  the  pollinium  and    ,  -,-,  ,         f        i  •    i 

viscid  disk  after  the   stimulation    tw°    P°llen    SaCS>   each    of    which 

of  the  spur  by  the  touch  of  an  contains  a   mass    of   pollen,  /. 

insect.    After  K.ERNER.  _,,  ,, 

The  pollen  masses  are  con- 
nected by  means  of  an  elastic  band  with  a  body  termed 
the  viscid  disk  d,  which  is  really  a  modified  portion  of  the 
stigmatic  part  of  the  column.  Running  down  from  the 
central  portion  of  the  column  are  two  slender  horns,  //, 
standing  in  the  way  of  insects'  which  would  gather  the 
nectar  or  eat  the  fleshy  parts  of  the  flower/ 

As  soon  as  an  insect's  head  touches  one  of  these  horns, 


FIG.  106. 


Flowers.  191 

a  stimulus  is  transmitted  to  the  column  resulting  in  the 
sudden  rupture  of  the  tissues  connecting  the  viscid  disk 
with  the  rest  of  the  column.  The  viscid  disk  is  then  jerked 
forward  by  means  of  the  elastic  band  with  sufficient  force 
to  pull  the  pollen  masses,  termed  pollinia,  from  their  pollen 
sacs  and  hurl  them  forward,  disk  foremost,  to  a  distance  of 
one  or  even  three  feet ;  but  if  the  insect  is  standing  in  the 
line  of  projection,  which  would  probably  be  the  case,  the 
viscid  disk  is  thrown  against  its  head  or  thorax  and  sticks 
there.  Thus  the  insect  is  made  to  carry  away  the  pollen 
masses,  which  are  sticking  out  forward  as  the  insect  enters 
the  next  flower. 

The  flower  just  described  is  known  as  the  male  flower, 
that  is,  the  pistil  is  abortive  and  does  not  bear  seed.  If 
the  insect  next  visits  a  female  flower,  having  a  perfect 
pistil  but  abortive  stamens,  the  pollinia  will  be  thrust  into 
a  concave  structure  known  as  the  stigmatic  chamber,  which 
has  an  adhesive  surface  capable  of  holding  the  pollinia 
with  sufficient  tenacity  to  wrest  them  from  the  insect. 
Then  the  pollen  tubes  grow  into  the  ovary  and  cross  fertili- 
zation of  the  eggs  is  accomplished. 

In  this  flower  we  see  a  marvelous  correlation  of  modi- 
fied parts  to  attain  a  definite  purpose ;  but  most  wonderful 
of  all  is  the  sudden  transmission  of  a  stimulus  due  to  the 
touch  of  the  insect  at  one  definite  part  of  the  flower,  and  a 
correspondingly  sudden  dissolution  of.  the  tissues  which 
hold  the  viscid  disk  in  place. 

140.  Cross  Pollination  of  Asclepias.  —  In  the  genus  Ascle- 
pias, we  find  an  adaptation  to  cross  pollination  by  insects 
scarcely  less  wonderful  than  that  of  the  orchids.  Asclepias 
cormtti  (Fig.  107),  common  everywhere  in  this  country,  is 
perhaps  the  best  species  for  demonstrating  this.  As  shown 
in  Fig.  108  the  sepals  (s)  and  petals  (/)  are  reflexed;  the 


Introduction  to  Botany. 


(r)  are  joined  throughout  their  length,  and  are 
united  to  a  thick  and  flat  structure  (t)  at  their  apices, 
known  as  the  stigmatic  disk,  which  is  also  united  with 

the  top  of  the  two 
pistils  (n).  The  pistils 
are  entirely  inclosed  by 

^&±  -$$  the    stamens    and    the 

JB      |^  Jf  stigmatic      disk.       Five 

spreading,  hollow  re- 
ceptacles (v)  for  the 
nectar  grow  out  and 
upward  from  the  bases 
of  the  stamens. 

Each  pollen  sac  con- 
tains a  compact  mass  of 
pollen  grains  (w)  which 
never  become  separated 
from  one  another,  and 
so  constitute  what  is 
termed  a  pollinium. 
The  two  contiguous  pol- 
linia  of  adjacent  anthers 
are  united  by  horny 
rods  (x)  which  converge 
upward  and  join  with  a 
horny  dark  body  (j/)  known  as  the  corpusculum,  which 
is  hollow  and  has  a  slit  along  its  outer  face.  This  slit 
is  relatively  broad  at  the  bottom,  and  tapers  toward  the 
top,  thus  forming  a  clip  in  which  the  feet  of  the  insects 
get  caught.  Between  each  pair  of  anthers  there  is  a 
deep  recess  closed  by  two  vertical  lips  which  stand  wider 
open  at  the  bottom  than  at  the  top,  and  the  recess  also 
narrows  at  the  top.  The  opening  between  the  lips  at 


FIG.  107. 
AscZepias  cornuti. 


Flowers. 


corpus- 


the   top   stands  exactly  beneath   the   slit   in 
culum. 

The  surface  of  the  flower 
is  slippery,  so  that  when  a 
bee,  for  instance,  visits  it, 
a  good  foothold  is  not  ob- 
tained until  the  bee  slips 
Its  foot  into  the  recess  be- 
tween the  anthers,  termed 
the  stigmatic  chamber  (m). 
Having  obtained  a  foot- 
hold, the  bee  thrusts  its 
sucking  apparatus  into  the 
hollow  nectar  receptacle 
and  obtains  the  nectar 
which  has  invited  it  to  the 
flower.  When  the  bee, 
however,  seeks  to  go  to 
another  flower,  its  foot 
slips  upward  and  becomes 
caught  in  the  slit  in  the 
corpusculum.  A  struggle 

now  ensues  which  usually 

FIG.  108. 

Diagram  of  a  flower  of  Asclepias  cornuti.  £,  surface  view  of  a  flower,  showing 
the  opening  into  the  stigmatic  chamber  at  m,  the  upward-pointing  nectar  recep- 
tacles, and  the  reflexed  petals.  F,  longitudinal  diagram  of  a  flower ;  s,  sepal ; 
p,  petal ;  n,  one  of  the  pistils ;  r,  stamen  and  nectar  receptacle  growing  from  it ; 
o,  pollen  sac ;  v,  nectar  receptacle,  with  stigmatic  chamber  between  it  and  the 
cavity  containing  the  pistils.  G,  cross  diagram  of  a  part  of  a  flower ;  m,  stig- 
matic chamber;  o,  pollen  sac;  n,  apices  of  the  pistils.  H,  diagram  showing 
the  relation  of  the  pollinia  to  the  stigmatic  chamber;  w,  pollinium ;  x,  connect- 
ing rod  or  retinaculum.  y,  corpusculum  or  clip.  The  pollinia  are  in  the 
pollen  sacs  and  the  clip  stands  over  the  stigmatic  chamber.  /,  semi-diagram- 
matic view  of  a  flower,  showing  the  pollinia  in  position  (as  if  the  pollen  sacs 
were  transparent)  ;  outline  of  pollen  sacs  shown  with  dotted  lines ;  at  the  top 
of  the  pollen  sacs  are  slits  through  which  the  pollinia  are  to  be  pulled  out. 
J,  showing  the  pollinia  partly  removed  from  the  pollen  sacs.  — WISE. 


194 


Introduction  to   Botany. 


results  in  the  bee  pulling  the  two  pollen  masses,  united 
to  the  corpusculum,  through  the  narrow  slits  (as  in  / 
and  J)  at  the  tops  of  the  pollen  sacs ;  and  thus  laden,  it 
seeks  another  flower,  and  there  slips  its  foot,  together 
with  the  pollen  masses,  into  the  stigmatic  chamber. 

Now  when  the  bee  attempts 
to  leave  the  flower,  the  pollen 
masses  become  tightly  wedged 
at  the  narrow  apex  of  the  cham- 
ber, and  a  hard  pull  is  required 
to  break  them  loose  from  the 
foot.  Finally,  as  the  foot  is 
being  drawn  from  the  stigmatic 
chamber  it  catches  into  the  cor- 
pusculum directly  above  and 
pulls  out  a  second  pair  of  pollen 
masses.  Thus  the  bee  goes  from 
flower  to  flower  and  from  plant 
to  plant,  repeatedly  pulling  pol- 

Photograph  of  a  honey  bee  gathering  . 

nectar  from  an  Asdepias  flower,  len  masses  from  their  sacs  and 
One  leg  is  still  fast  in  a  stigmatic  depositing  them  in  the  stigmatic 

chamber  of  the  flower  last  visited. 

chambers.  Figure  109  is  a  pho- 
tograph of  a  honey  bee  gathering  nectar  from  Asdepias 
flowers.  One  of  the  hind  legs  is  still  held  in  the  stigmatic 
chamber  of  the  flower  which  the  bee  has  just  deserted. 
Referring  to  Diagram  G,  note  that  the  pollinia  are  re- 
moved by  the  bee  from  the  pollen  sacs  o,  o,  and  de- 
posited in  another  flower  in  the  stigmatic  chamber  m. 
The  bee  always  inserts  its  foot  in  m  both  in  removing 
the  pollinia  and  in  depositing  them. 

While  the  honey  bee  is  the  most  important  cross  pollina- 
tor of  this  plant,  butterflies  and  wasps  are  also  of  service. 

After  the  pollinia  have  been  deposited  in  the  stigmatic 


FIG.  109. 


Flowers. 


'95 


FIG.  no. 

Photograph  of  a  Cabbage  Butterfly  caught  by 
its  legs  in  the  corpuscula  of  two  Asclepias 
flowers  and  unable  to  escape. 


chamber,  they  put  forth  pollen  tubes  which  penetrate  to 

the   tips   of    the   styles, 

and    then    turn     down- 
ward and  find  their  way 

to  the  ovules. 

A    useful    insect     is 

rarely  held  in  captivity 

by    the     flower,     while 

weak    insects,    or    their 

legs    which    have    been 

pulled  off  in  their  strug- 
gle to  free  themselves, 

are  often  found  hanging 

to  corpuscula  that  have 

not  been  removed  from 

their    original    places. 

Figures   no  and  in  illustrate  instances  of  this  kind. 
Rarely,  indeed,  a  honey  bee,  too   eager  in  its  search 

for  nectar,  becomes  caught 
in  many  flowers  at  once,  and 
is  unable  to  extricate  itself 
(Fig.  112). 

Figure  113  is  a  photo- 
micrograph of  a  pair  of 
pollinia  attached  to  their 
common  corpusculum,  and 
Figure  114  is  a  photograph 
of  a  bee's  leg  with  four 
corpuscula  and  two  pollinia 
attached.  There  the  second 
corpusculum  has  caught  on 
one  arm  from  the  first,  and 
so  on. 


\   \ 


FIG.  in. 


Photograph  of  a  Moth  with  its  legs 
caught  in  the  corpuscula  of  three 
Asclepias  flowers,  one  leg  having 
been  pulled  off  in  its  vain  efforts  to 
extract  the  pollinia  and  escape. 


196 


Introduction  to  Botany. 


141.  Cross  Pollination  of  Yucca. — Thus  far  we  have  taken 
for  our  illustrations  flowers  which 
are  more  or  less  profoundly  modi- 
fied to  secure  cross  pollination  as 
a  necessary  incident  attending 
the  visits  of  insects.  We  shall 
now  examine  an  instance  of  quite 
another  character,  and  in  some 
respects  even  more  wonderful 
^^^_  than  those  which  have  been 

FIG.  112.  described.     The  flowers  of  the 

Photograph  of  a  honey  bee  that  has  genus  Yucca,  representatives  of 

died  from  exhaustion  in  its  efforts  . 

to  free  itself  after  its  legs  had  been  which   are   commonly  found   in 

gardens,  depend  almost  entirely 
upon  the  Pronuba  moth  for  their 
pollination.  The  structure  of  the  flower  is  very  simple  and 
readily  understood.  The 
perianth  is  of  the  lilia- 
ceous type,  there  being 
three  sepals  and  three  pet- 
als, all  of  a  creamy  white 
color.  In  some  of  the 
Yuccas  these  droop  for- 
ward and  form  bell-shaped 
flowers,  while  in  others 
they  are  more  widely 

Spreading.       The    Six    Sta-    Photomicrograph  of  a  pair  of  pollinia  of  As- 

mens    Consist     Of     fleshy,        clePias  cornuti  attached  to  their  corpuscu- 

.  lum,  as  they  appear  when  withdrawn  from 

OUtward-CUrving  filaments  their  pollen  sacs.  Photographed  by  trans- 
mitted light,  and  on  account  of  the  opacity 
of  the  corpusculum  the  slit  in  it  is  not  shown, 
but  a  portion  of  a  leg  of  a  small  insect  is 
pendent  from  the  slit.  The  pollen  grains 
of  which  the  pollinia  are  composed  can  be 
made  out.  X  15. 


surmounted  by  small  an- 
thers. The  pistil  extends 
beyond  the  stamens,  and 
the  three  carpels  are  im- 


Flowers. 


197 


perfectly  united  at  the  top,  leaving  a  tube  entirely  open 

at  the  apex.     The  inner  surface  of  this  tube  is  stigmatic. 

The    stigmatic    tube    does    not 

open  directly  into  the  cavities 

of    the    ovary,    but    sends    off 

three    very    narrow     branches, 

each    of    which    communicates 

with    the    cavity   of    a    carpel. 

Accordingly,    when     pollen    is 

once    deposited    on    the    inner 

surface  of   the   main   stigmatic 

tube,  the  pollen  tubes  find  easy 

access  to  the  ovules  in  each  of 

the  three  carpels.     The  pollen 

is  sticky  and  hangs  together  in 

masses,  so  that  it  is  not  adapted 

to  being  carried  by  the  wind, 

and  it  is  apparently  impossible 

for  it  to  get  to  the  stigmatic  tube  without  some  outside 

agent. 

A  small  amount  of  nectar  is  secreted,  but  it  is  excreted 
at  the  very  base  of  the  pistil,  so  that  insects  seeking  it  would 
be  far  removed  from  the  stigmas.  Indeed,  the  low  position 
of  the  nectar  would  seem  rather  to  lead  insects  away  from 
the  stigmas.  The  flowers  are  borne  in  compound  racemes 
high  aloft  on  a  strong  woody  shaft,  and,  because  of  their 
rather  strong  odor  when  new  buds  are  opening  in  the 
evening  and  their  white  color,  they  are  quite  certain  to 
make  their  presence  known  to  insects  flying  in  the 
twilight  (see  Fig.  115). 

If  we  take  these  facts  as  our  clew  and  attentively  watch 
these  flowers  about  eight  o'clock  in  the  evening,  the  method 
of  cross  pollination  will  be  made  clear.  A  white  moth, 


FIG.  114. 

Photomicrograph  of  the  leg  of  a 
honey  bee  with  a  chain  of  four 
corpuscula  clinging  to  it.  The 
last  two  corpuscula  are  still  bear- 
ing one  pollinium  each;  the  re- 
maining six  pollinia  have  doubt- 
less been  deposited  by  the  bee  in 
stigmatic  chambers.  X  5. 


198 


Introduction  to  Botany. 


known  as  the  Pronuba  moth,  is  seen  to  mount  a  stamen, 
scrape  together  the  sticky  pollen,  and  pack  it  against  the 
under  side  of  its  head  by  means  of  a  spinous  structure 
known  as  the  maxillary  tentacle,  which  seems  to  have  been 
specially  developed  for  this  purpose,  for  in  other  moths  it 


FIG.  115. 
Yuccas  in  the  twilight.     Drawn  from  a  photograph. 

is  a  mere  vestige.  In  gathering  the  pollen  it  hooks  its 
tongue  over  the  end  of  the  stamen,  evidently  to  secure  a 
better  hold  (see  Fig.  116).  Having  become  well  loaded 
with  pollen,  as  shown  in  the  photomicrograph  of  the  moth's 
head  (Fig.  117),  it  descends  the  stamen  and  flies  to  another 
flower.  There  it  places  itself  on  the  pistil  between  two  of 


Flowers. 


199 


the  stamens  (see  Fig.  118)  and  thrusts  a  slender  ovipositor 
through  the  wall  of  the  ovary  and  into  the  cavity  occupied 
by  the  ovules. 

Having  deposited 
an  egg,  it  ascends  the 
pistil,  and  by  means 
of  the  maxillary  ten- 
tacles and  tongue, 
which  at  other  times 
are  coiled  around  the 
load  of  pollen,  as  seen 

in   Fig.    117,   it  rubs      ^  FlG  Ii? 

pollen  down  the  inner     jPktf  Photomicrograph  of  the  head 

surface    of    the    stip--     *  and  fore  part  of  the  body  of 

g  FIG  116  a  Pronuba  moth,  showing  the 

matic    tube.        Figure   pronubamothgath-     tongue  and  maxillary  tentacles 

119    is    a    flashlight     ering    pollen.    £°|£ keUnetth  thT?idf  P°x6n 

photograph  of  a  moth 

performing  this  act.  The  moth  then  descends  the  pistil,  and 

standing  between  another 
pair  of  stamens  it  deposits 
another  egg  within  the 
ovary ;  then  it  ascends  the 
pistil  and  rubs  pollen  on 
the  stigmatic  surface  as  be- 
fore. This  process  is  re- 
peated until  it  may  be  that 
each  of  the  six  lines  of 
ovules  is  provided  with  an 
egg,  and  the  process  of  pol- 
lination has  been  as  many 
FlG-  II8-  times  accomplished. 

Pronuba  moth  depositing  its  eggs  in  the  The  fu\\   meaning  of  this 

ovary  of  a  yucca  flower.      Flashlight 
photograph  taken  about  8.30  P.M.  WOndertul    SCriCS   OI    Opera- 


2OO 


Introduction  to  Botany. 


tions  will  not  be  understood  until  subsequent  developments 
have  been  followed.  Since  the  process  of  pollination  has 
been  so  thoroughly  done,  most  of  the  numerous  ovules 
become  fertilized  and  the  seeds  begin  their  development. 

In  the  meantime  the  moth 
eggs  hatch  into  larvae, 
which  find  their  food  in 
the  developing  seeds.  But 
the  seeds  are  so  numerous 
that  the  larvae  reach  their 
growth,  gnaw  a  hole  in 
the  seed-pod  and  escape, 
while  many  uninjured 
seeds  still  remain  in  the 
pod.  The  larva  spins  a 
thread  by  which  it  de- 
scends to  the  ground,  and, 
burro  wing  beneath  the  sur- 
face, it  passes  the  winter  in 
its  pupal  state,  emerging  as 
a  fully  developed  moth  at  the  time  of  the  flowering  of  the 
Yucca  the  following  summer. 

It  appears  that  the  mature  moth  takes  no  food,  unless 
it  secures  some  of  the  nectar  of  the  Yucca  blossoms  in 
which  it  is  wont  to  pass  the  day,  with  its  head  close  to 
the  bottom  of  the  flower  where  the  nectar  is  excreted.  It 
does  not  eat  the  pollen  which  it  gathers,  and  it  seems  cer- 
tain that  it  is  prompted  to  place  the  pollen  in  the  stigmatic 
tube  after  each  act  of  oviposition  solely  by  the  instinct  to 
provide  for  its  young ;  for  it  is  readily  understood  that  if 
the  ovules  are  not  fertilized  the  seeds  would  not  develop 
and  the  larvae  would  be  without  food. 

The  Yucca  flower,  instead  of  having  elaborate  devices 


FIG.  119. 

Pronuba  moth  rubbing  pollen  down  the 
stigmatic  tube  of  a  yucca  flower.  Flash- 
light photograph  taken  about  8.30  P.M. 


Flowers.  201 

to  secure  cross  pollination,  simply  prohibits  self  pollina- 
tion by  its  tubular  stigmas  and  its  relatively  short  and 
reflexed  stamens;  and  then,  the  sticky  pollen  and  an 
abundance  of  ovules  being  provided,  the  performance  of 
pollination  is  intrusted  to  the  wise  instinct  of  the  Pronuba 
moth ;  and  not  pollination  simply,  but  cross  pollination,  for 
it  has  been  noticed  that  it  is  the  habit  of  the  moth  after 
securing  the  pollen  to  fly  to  another  flower  before  it  begins 
to  lay  its  eggs.  We  wonder  how  such  an  instinct  could  have 
been  evolved,  and  how  the  moth  and  the  plant  came  to  be 
so  intimately  associated  and  so  absohitely  necessary  to  each 
other's  existence.  It  seems  certain  that  they  have  come 
through  the  long  years  of  their  race  history  together,  and 
that  each  has  been  affected  by  the  modifications  of  the  other. 

Sufficient  illustrations  have  now  been  given  to  show  the 
student  that  there  is  a  wide  and  attractive  field  for  study 
in  the  structure  and  behavior  of  flowers  ;  for  they  afford 
us  not  only  the  best  evidence  of  the  relationships  of  plants 
(see  Chapter  XVII),  but  they  also  reveal  to  us  a  mutually 
beneficent  association  of  plants  and  animals,  and  the  mar- 
velous plasticity  of  plants  in  molding  the  forms  of  their 
parts  and  responding  to  external  forces  and  internal  condi- 
tions in  such  a  way  as  to  meet  any  required  end. 

142.  The  Morphology  of  a  Flower.  —  In  doing  the  work 
in  the  chapter  on  Modified  Parts,  the  student  has  become 
familiar  with  the  methods  of  seeking  out  morphological 
evidence,  and  he  should  now  test,  with  all  the  evidence 
obtainable  by  him,  the  following  statement  of  the  morphol- 
ogy of  a  flower:  A  flower  is  a  branch  with  much  shortened 
internodes  (termed  the  receptacle)  whose  growth  in  length 
is  terminated  by  the  production  of  spore-bearing  leaves 
(stamens  and  carpels);  the  most  complete  flowers  also 
having  modified  leaves  in  the  form  of  sepals  and  petals. 


102 


Introduction  to   Botany. 


In  order  to  understand  the  morphology  of  the  parts  of  a 
flower  we  must  refer  back  to  simpler  and  older  types  of 
vegetation.  The  Lycopodiums  or  club  mosses  are  repre- 
sentatives of  an  ancient  group  of  plants  which  reached  its 

maximum  development  in  the 
Carboniferous  period.  There 
are  good  reasons  for  the  belief 
that  the  Lycopodiums  and  the 
flowering  plants  are  offshoots 
from  a  common  ancestral 
stock,  the  Lycopodiums  be- 
ing, of  the  two,  much  less 
modified  and  more  primitive 
in  character.  We  find  in  them 
that  the  stem  is  thickly  beset 
with  small,  awl-shaped  leaves 
(Fig.  120).  Near  the  apex  of 
the  stem  some  of  the  leaves 
bear  spore  cases  or  sporangia 

In 


FIG.  120. 


gregated  into  cones  at  the  apices  of    species     the     Spore-bearing 

the  branches;  2,  a  leaf  from  the  cone,    ,  1 7     ,, 

with  a  sporangium  in  its  axil ;  3  and    leaves       Or       Sporophylls       are 

4,  spores  from  the  sporangium.  After  broader    and    longer-pointed 

WOSSIDLO.  if  -  f    ..  , 

than  the  foliage  leaves,  but 

there  may  be  all  degrees  of  gradation  between  the  two 
forms.  In  other  species  there  may  be  no  difference  in 
appearance  between  the  foliage  leaves  and  sporophylls. 
In  some  species  the  sporophylls  are  aggregated  into  a 
cone,  in  others  not. 

In  the  Lycopodiums  the  sporangia  and  spores  are  of  one 
kind  only;  but  in  the  somewhat  nearly  related  genus 
Selaginella,  there  are  two  sorts  of  sporangia,  borne  each  on 
the  stem  in  the  axil  of  the  sporophyll,  which  in  general 


Flowers. 


203 


m 


does  not  differ  from  a  foliage  leaf  in  appearance.  One 
kind  of  sporangium  contains  relatively  small  spores  termed 
microspores  (Fig.  121)  which  on  germination  give  rise  to  a 
rudimentary  plant  body  called  prothallium,  bearing  sperm 
cells ;  and  the  other  sort  of  sporangium  contains  relatively 
large  spores,  the  macro- 
spores  (Fig.  12 1),  which 
on  germination  produce  a 
prothallium  bearing  egg 
cells.  The  sporangium 
containing  macrospores 
is  termed  macrosporan- 
gium,  and  the  sporophyll 
subtending  it  macrosporo- 
phyll,  while  the  corre- 
sponding parts  relating  to 
the  microspores  are  called 
micro  sporangium  and  mi- 
crosporophyll. 

Now,  in  a  flower,  since 
the  pollen  grain  produces 
the  sperm,  it  must  be  a  microspore,  the  anther  a  microspo- 
rangium,  and  the  entire  stamen  a  modified  microsporophyll. 
The  large  cell  in  the  ovule  (termed  embryo  sac}  which  pro- 
duces the  egg  must  be  the  macrospore,  and  the  ovule  the 
macrosporangium,  while  the  pistil  evidently  corresponds  to 
a  macrosporophyll  with  the  edges  infolded  and  grown 
together  forming  an  inclosed  chamber.  Each  sporophyll 
taking  part  in  the  formation  of  a  pistil  is  called  a  carpel. 
Or  the  pistil  may  be  composed  of  more  than  one  sporophyll 
united,  as  indicated  by  the  number  of  styles,  stigmas,  or 
groups  or  rows  of  ovules.  When  composed  of  a  single 
sporophyll  or  carpel  the  pistil  is  said  to  be  simple,  when  of 


FIG.  121. 

i,  Selaginella.  Toward  the  summit  of  the 
plant  the  leaves  are  more  pointed,  and  they 
become  aggregated  into  a  cone-like  group 
at  the  apex.  2,  Microsporangium,  m, 
discharging  microspores ;  n,  macrosporan- 
gium containing  macrospores.  After 
STRASBURGER. 


204 


Introduction  to   Botany. 


FIG.  122. 

Transition  between  stamens  and  petals  in 
Nymphcea  odorata.    After  GRAY. 


more  than  one,  compound.  The  sepals  and  petals  may  be 
either  modified  foliage  leaves  or  barren  sporophylls.  Evi- 
dence that  they  may  be 
the  latter  is  found  in  the 
fact  that  all  gradations  of 
transition  between  sta- 
mens and  petals  occur  in 
the  sweet-scented  pond 
lily,  Nymph&a  odorata 
(Fig.  122),  and  in  various 
double  flowers.  But  on 
the  other  hand  all  de- 
grees of  gradation  may  be 
found  from  foliage  leaves, 
through  sepals  and  petals 
to  stamens,  so  that  along  this  line  of  evidence  we  cannot 
come  to  a  positive  conclusion.  Since  in  the  relatively 
ancient  -  Lycopodiums  and  Selaginellas  there  may  be  no 
difference  in  appearance  between  the  foliage  leaves  and 
sporophylls,  and  in  others  there  may  be  all  degrees  of 
gradation  between  them,  it  would  seem  that  foliage  leaves 
and  sporophylls  have  had  a  common  origin. 

The  relative  positions  of  the  different  parts  of  flowers  may 
show  considerable  variation,  as  seen  in  diagrams  of  row  </, 
A,  B,  C,  D,  of  Fig.  123.  When  the  parts  arise  near  to- 
gether on  the  apex  of  the  receptacle  (d,  A),  the  pistil  is 
said  to  be  superior  and  the  flower  hypogynous.  When  the 
outer  part  of  the  receptacle  is  prolonged  into  a  tube  or  cup 
carrying  the  sepals,  petals,  and  stamens  above  the  in- 
sertion of  the  pistil  (d,  B),  the  pistil  is  called  half  inferior 
and  the  flower  perigynous.  When  the  zone  of  the  re- 
ceptacle bearing  sepals,  petals,  stamens,  and  carpels  is 
prolonged  in  the  form  of  a  hollow  tube  or  cup  which  forms 


Flowers. 


205 


the  outer  wall  of  the  ovary  (d,   C),  the  pistil  is  called 
inferior  and   the   flower    epigynous.     In   determining  the 


iff 


Diagrammatic  representation  of  the  embryology  of  (A)  hypogynous,  (B)  perigy- 
nous,  and  (Cand  D)  epigynous  flowers.  The  receptacle  is  dotted,  the  sepals 
and  stamens  are  unshaded,  the  petals  are  black,  and  the  pistil  ruled  horizontally. 
In  such  flowers  as  B  and  D  the  tubular  extension  of  the  receptacle,  commonly 
called  the  tube  of  the  corolla,  may  be  considered  a  distinct  member  of  the  flower, 
termed  the  ring  leaf.  (See  Ganong,  "  The  Teaching  Botanist.")  After  GANONG. 


206 


Introduction  to   Botany. 


identity  of  the  parts  of  perigynous  and  epigynous  flowers 
their  embryology  must  be  called  in  evidence.  It  is  seen 
that  the  parts  of  a  flower  first  arise  as  minute  lobes  of  the 
receptacle,  as  at  a  in  the  diagrams.  In  hypogynous 
flowers  the  plane  of  insertion  of  the  lobes  remains  nearly 
the  same  throughout  the  development  of  the  flower  (a,  b, 
c,  d,  A).  In  perigynous  flowers  the  outer  zone  of  the 
receptacle  is  soon  found  to  extend  upward  so  that  the 
insertion  of  the  sepals,  petals,  and  stamens  is  raised  to  a 

higher  plane  (a,  b,  c,  d,  B). 
In  epigynous  flowers  a 
broader  zone  of  the  recep- 
tacle grows  upward,  carry- 
ing higher  the  planes  of 
insertion  of  all  of  the  floral 
parts  (a,  b,  c,  d,  C).  In  pe- 
rigynous flowers  (B)  the 
hollow  extension  of  the  re- 
ceptacle may  vary  greatly 

Longitudinal  diagrams  of  the  flowers  of      jn  height,  thickness,  texture, 
(a)  rose,  (b)  plum,  (c)  Solomon's  seal. 

and  color;  it  may  be  thick 

and  cup-shaped,  as  in  the  cherry  and  plum  (Fig.  124); 
urn-shaped  and  contracted  at  the  summit,  as  in  the  rose ; 
thin  and  corolla-like,  as  in  Solomon's  seal  and  hyacinth, 
where  it  is  commonly  called  the  perianth  tube.  In  epigy- 
nous flowers  there  may  be  a  tubular  extension  of  the 
receptacle  beyond  the  pistil,  as  in  fuchsia  (Fig.  123,  D)\ 
or  an  extension  of  the  receptacle  may  form  a  solid  shaft 
surmounting  the  ovary,  bearing  sepals,  petals,  stamens, 
and  styles  at  its  summit,  as  in  Iris.  But  in  this  instance, 
and  in  some  others  where  the  pistil  is  inferior,  it  may  be 
that  the  inner  portion  of  the  outer  wall  of  the  ovary  is 
carpellary  tissue  adherent  to  the  hollow  receptacle. 


CHAPTER   IX. 

DISPERSION  OF  FRUITS  AND  SEEDS. 
PROVIDING  MATERIAL. 

Since  the  fruits  and  seeds  of  many  plants  mature  after  the  work  of 
the  school  year  is  completed,  it  is  advisable  to  gather  the  most  interest- 
ing forms  as  they  mature,  and  preserve  them  for  the  work  of  the  suc- 
ceeding year.  Seeds  and  fruits  with  wings,  barbs,  hooks,  etc.,  may  be 
dried  and  stored  in  boxes  or  any  convenient  receptacles.  Seeds  with 
delicate  hairs  serving  as  parachutes,  etc.,  should  be  gathered  shortly 
before  their  pods  break  open,  and  stored  in  pasteboard  boxes.  When 
the  pods  are  large,  it  is  a  good  plan  to  tie  them  so  they  cannot  burst 
open  on  drying.  The  pods  of  milkweed  and  dogbane,  for  instance, 
may  be  treated  in  this  way.  Fleshy  fruits  should  be  gathered  in  dif- 
ferent stages  of  development  and  preserved  in  formalin. 

OBSERVATIONS. 

135.  Follow  the  development  of  the  pistil  after  pollina- 
tion, in  the  cases  of   some  of   the  flowers  studied  in  the 
laboratory  or  in  the  field,  and  note  what  changes  it,  or  any 
parts  connected  with   it,  undergo.     Interesting  examples 
may   be   found    in   the    strawberry,   anemone,   rose,   crab 
apple,  gooseberry,  plum,  larkspur,  violet,  oxalis,  geranium, 
milkweed,  spurge,  cottonwood,  hornbeam,  hop  hornbeam, 
oak,  walnut,  hazelnut,  maple,  sumac,  catalpa,  climbing  bit- 
tersweet. 

136.  Make  drawings  of   fruits  having  hooks,  anchors, 
etc.,  by  means  of  which  they  cling  to  animals  and  become 
scattered  by  them.     Typical  forms  of  this  sort,  of  common 

207 


208  Introduction  to   Botany. 

occurrence,  are  the  cocklebur,  burdock,  black  snakeroot, 
common  beggar  ticks,  etc. 

137.  Make  drawings  of  seeds  or  fruits  which  are  adapted 
to  being  carried  about  by  the  wind.     Good  examples  are 
dandelion,  maple,  elm,  milkweed,  dogbane,  pine,  golden- 
rod,  and  feathergrass. 

138.  Make  drawings  and  notes  showing  the  method  of 
dispersion  of   the  seeds  of    some  water   plants,  such    as 
those  of  pond  lilies. 

139.  In  your  notes  discuss  briefly  the  following  ques- 
tions :  Of  what  advantage  to  the  species  is  it  for  plants  to 
produce  edible  fruits?     Would  the  minute  ripened  pistils 
of   the  strawberry,  or  the  small  seeds  of   the  fig,  grape, 
gooseberry,  etc.,  be  apt  to  be  broken  when  the  seeds  are 
eaten  ?     Of  what  advantage  is  the  bitter  taste  of  the  seeds 
of  the  orange  ?    What  common  plants  probably  have  their 
seeds  scattered  by  birds  ? 

140.  Determine  the  morphology  of  the  various  devices 
for  dissemination  in  the  fruits  and  seeds  studied,  and  record 
observations  and  conclusions  in  your  notes. 

141.  Count  the  number  of   seedlings  which  spring  up 
in  one  square   foot  of   ground,  and    as   they  grow  older 
note  how  many  of  them  succumb  in  the  competition  for 
food  and  light. 

DISCUSSION. 

143.  Importance  of  Seed  Dispersion.  —  A  moment's  re- 
flection will  convince  the  student  that  the  dispersion  of  the 
seed  to  some  distance  from  the  parent  plant  is  of  vital  im- 
portance to  the  continuance  and  well-being  of  the  species. 
If  the  seeds  were  to  fall  immediately  beneath  the  plant,  a 
crowd  of  offspring  would  result,  growing  so  close  together 
as  to  deprive  each  other  of  a  sufficient  amount  of  sunlight 


Dispersion  of  Fruits  and  Seeds.  209 

and  raw  materials  from  the  soil.  Or,  if  the  parent  were  a 
perennial,  it  would  overshadow  and  starve  the  seedlings. 
Even  with  some  means  of  seed  dispersion,  there  is  apt  to 
be  greater  competition  between  individuals  of  the  same 
species  than  between  those  of  different  species,  because 
plants  of  the  same  species  require  the  same  proportions  of 
the  different  soil  constituents,  and,  having  the  same  habit 
of  growth,  crowd  each  other  more  than  the  same  number 
of  individuals  of  different  species  distributed  over  the  same 
area  would  be  apt  to  do.  One  need  only  compare  the 
number  of  seedlings  of  a  particular  species  appearing  above 
the  soil  in  a  given  area  with  the  number  of  those  which 
actually  reach  maturity  in  the  same  area  to  be  convinced 
of  the  struggle  which  is  taking  place  among  them,  with 
fatal  results  except  to  the  relatively  few  individuals  which 
are  stronger  and  more  rapid  growers  than  their  fellows. 
Any  devices  which  aid  in  dispersing  the  seed  help  to 
ameliorate  these  conditions. 

144.  Migration  by  Seeds.  —  The  dispersion  of  seeds  and 
other  reproductive  bodies  has  been  of  vital  importance  to 
plants  in  another  way :  The  climate  of  the  earth  has  been 
undergoing  profound  changes  through  the  long  geological 
periods.  In  some  places  a  temperate,  or  even  a  warm, 
climate  has  given  way  to  a  frigid  one ;  and  then  after  a 
long  time  the  temperate  climate  has  returned.  By  means 
of  fruits  and  seeds  capable  of  dispersion,  plants  have  been 
able  to  recede  before  the  advancing  cold,  when  without 
this  power  they  would  have  become  extinct.  And  finally 
when  the  warmer  climate  returned,  they  have  been  able  to 
follow  the  retreating  ice  back  toward  the  arctic  circle. 

In  the  same  way  they  have  taken  possession  of  land 
which  has  risen  on  the  borders  of  continents,  or  far  out  in 
the  oceans  in  the  form  of  volcanic  or  coral  islands,  and  of 


210 


Introduction  to  Botany. 


the  rich  deposits  which  have  accumulated  at  the  mouths 
of  rivers.  Much  of  the  variation  resulting  in  the  great 
multiplicity  of  form  and  structure  which  we  now  see  has 
originated  in  the  different  environments  found  by  plants 
by  means  of  their  migrant  seeds. 

We  see,  then,  that  from  many  points  of  view  it  is  im- 
portant to  plants  to  produce  reproductive  bodies  capable 

of  dispersion  by  their  own 
movements  or  by  natural 
agents  outside  of  them- 
selves, such  as  the  wind, 
running  water,  birds,  in- 
sects, etc. ;  and  we  may 
expect  to  find  a  great  vari- 
ety of  devices  intended  to 
facilitate  the  scattering  of 
fruits  and  seeds. 

145.  Dispersion  by  Elas- 
tic Tissues.  —  The  seeds 
of  the  wild  cranesbill  are 
scattered  by  a  sudden  springing  outward  of  the  valves  of 
the  carpels.  This  action  is  caused  by  the  outer  layers  of 
cells  being  more  succulent  and  shrinking  more  on  drying 
than  the  inner  layers.  The  ripened  seeds  lie  loosely  in 
the  inflated  lower  portion  of  the  carpels,  and  are  conse- 
quently thrown  out  when  the  carpels  spring  upward  (see 
Fig.  125). 

When  the  fruits  of  the  common  Euphorbias  are  picked 
and  placed  on  a  table  in  a  dry  room,  the  carpels  suddenly 
spring  apart  as  they  become  dry,  and  hurl  the  seeds  with 
considerable  force  to  various  parts  of  the  room.  Of  course 
they  act  in  the  same  way  under  natural  conditions  out  of 
doors. 


FIG.  125. 

Elastic  carpels  of  Cranesbill ;  seed  being 
thrown  on  the  right.     After  KERNER. 


Dispersion  of  Fruits  and  Seeds.  in 


The  behavior  of  the  seed  pods  of  the  wild  and  cultivated 
touch-me-nots  is  familiar  to  every  one.  Here  the  valves 
of  the  pods  suddenly  coil  elastically  when  touched,  and 
scatter  the  seeds. 

In  many  plants  the  carpels  break  apart  in  such  a  way  as 
to  allow  the  seeds  to  lie  loosely  in  them,  so  that  when  the 
plant  is  violently  shaken  by 
the  wind,  or  when  it  sud- 
denly rebounds  after  being 
bent  down  by  passing  ani- 
mals, the  seeds  are  thrown 
from  their  position.  In 
many  composite  plants  the 
dry  fruits  which  lie  loosely 
on  the  receptacle  are  scat- 
tered in  this  way,  the  stems 
having  become  dry  and 
elastic  by  the  time  the 
fruits  have  ripened. 

A  very  curious  case  where 
the  elasticity  of  succulent 
tissues  is  employed  is  found 
in  the  squirting  cucumber 

(Fig.  126).  When  the  fruit  ripens,  a  portion  of  it  in  the 
form  of  a  plug  continues  with  the  stalk,  becomes  sepa- 
rated from  the  surrounding  tissues  while  still  remaining 
attached  to  the  stalk,  and  is  drawn  out  like  a  stopper 
when  the  fruit  drops  off.  Then  the  swollen  mucilaginous 
contents  which  had  kept  the  walls  of  the  fruit  in  a  state  of 
tension  are  forcibly  ejected,  together  with  the  seeds,  by 
the  sudden  contraction  of  the  walls. 

146.  Dispersion  by  Winds.  —  A  common  device  designed 
to  employ  the  wind  as  an  agent  of  dispersion  is  found  in 


FIG.  126. 


A  branch  of  squirting  Cucumber,  showing 
a  fruit  falling  off  and  ejecting  the  seeds. 
After  KERNER. 


FIG.  127. 

Various  devices  for  Seed  Dispersal.  Arrangements  for  dispersal  by  means  of  the 
wind  are  shown  at  a,  seed  of  a  Bignonia;  d,  fruits  of  Ailanthus;  e,  seed  of 
Salix  myrsinitis  ;  g,  fruit  of  Geum  montanum  ;  i,  fruits  of  Tilia,  where  a  bract 
serving  as  a  wing  adheres  to  the  fruiting  peduncle ;  /,  fruits  of  Taraxacum,  where 
the  modified  calyx  or  pappus  acts  as  a  parachute;  »,  fruits  of  Acer.  Devices 
for  catching  hold  of  passing  animals  are  shown  at  c,  fruit  of  Bidens  bipinnata; 
h,  Hedysarum  Canadense,  the  jointed  fruits  of  which  are  beset  with  hooks,  as 
shown  at  / ;  m,  fruit  of  cocklebur.  Sticky  glandular  hairs  covering  the  calyx 
containing  ripened  fruits  occur  in  /  Salvia  glutinosa  ;  the  magnified  hairs  are 
shown  adhering  to  an  object  at  k.  Hurling  the  fruits  from  a  catapult  formed  by 
the  persistent  calyx  and  elastic  pedicel  occurs  in  Teucrium  Euganteum  at  b ; 
here  projection  occurs  when  the  plant  is  shaken,  etc.  Creeping  of  fruits  by  the 
hygroscopic  movement  of  arms  and  hairs:  o,  &gilops  ovata;  p,  Crupina  vul- 
garis.  After  KERNER. 


Dispersion  of  Fruits  and  Seeds. 


213 


FIG.  128. 

Seed  pod  of  Trumpet  Creeper  broken  open  and  winged 
seeds  fallen  out.     Reduced. 


those  seeds  and 

fruits  with  out- 
growths  in    the 

form  of  sails  or 

wings.      In    the 

case     of     elms, 

maples,      Ailan- 

thus,  etc.  (a,  d, 

n,  Fig.  127),  the 

border     of     the 

ovary  grows  out 

in  the  form  of  a 

membrane ;  and 

in  the  seeds  of  the  Catalpa  and  trumpet  creeper  (Fig.  128) 

the  walls  of  the  seeds  behave  in  a  similar  manner. 

One  of  the 
best  devices  to 
give  buoyancy 
to  light  seeds  or 
fruits  is  an  out- 
growth of  hairs, 
such  as  is  found 
on  the  fruits  of 
dandelion  or 
Anemone,  or  on 
the  seeds  of  the 
poplars,  milk- 
weeds (Fig.  1 29), 
cotton  of  com- 
merce, etc. 

In  the  cotton- 
wood  (Populus 


FIG.  129. 


Seed  pod  of  Asclepias  cornuti  and  escaping  seeds.     The 

tuft  of  hairs  on  each  seed  acts  as  a  parachute.    Reduced.     1H  0  111  I IJ  6  V  d  j  , 


2I4 


Introduction  to  Botany. 


FIG.  130. 

Seed  pods  of  the  Cottonwood 
just  before  breaking  open. 
Reduced. 


where  the  hairs  are  an  outgrowth 
from  the  base  of  the  seed,  the  total 
weight  of  the  seed  and  hairs  is  1.5 
milligrams;  while  in  the  seed  pod 
the  hairs  are  closely  appressed 
against  the  seed,  but  after  the  pod 
breaks  open  the  hairs  begin  to  dry 
and  bend  downward  and  outward, 
and  in  so  doing  they  assume  the 
form  of  a  parachute  and  spread  the 
seeds  apart  at  the  same  time,  so 
that  the  slightest  puff  of  wind  car- 
ries them  away.  On  a  single  tree 
the  pods  may  be  breaking  open  in 
succession  and  offering  their  seeds 
to  the  wind  for  a  space  of  two 
months,  so  that  the  seeds  are  quite 


certain  to  be  borne  away 
by  winds  from  all  direc- 
tions. In  strong  winds, 
such  seeds  must  be  car- 
ried to  very  great  dis- 
tances (Fig.  131). 

In  the  tumbleweeds 
another  method  has  been 
devised  for  employing 
the  wind  in  scattering 
the  seeds.  These  plants 
have  a  rounded  general 
contour;  when  the  seeds 
have  ripened,  the  whole 
plant  dies  and  breaks  off 
close  to  the  ground,  and 
is  easily  rolled  by  the 


FIG.  131. 

On  the  left  seed  pods  of  Cottonwood  breaking 
open  and  the  hairs  on  the  seeds  beginning  to 
spread  apart  and  push  the  seeds  out  of  the 
pods ;  on  the  right,  a  later  stage,  the  seeds 
ready  to  be  wafted  away  by  the  wind.  Reduced. 


Dispersion  of  Fruits  and  Seeds.  215 

wind  across  open  spaces,  the  seeds  being  scattered  from 
their  pods  during  the  journey.  It  is  this  tumbling  habit 
which  helps  to  make  the  Russian  thistle  such  a  troublesome 
pest. 

147.  Dispersion  by  Birds.  —  The  birds  are  the  most  effec- 
tive agents  among  animals  for  distributing  seeds.     They 
often  swallow  berries  and  other  pulpy  fruits  whose  seeds 
are  too  small  or  hard  to  be  broken  up  in  the  gizzard,  and 
are  finally  ejected  undigested  and  capable  of  germination. 
Such  berries  are  usually   inconspicuous  and  unpalatable 
until  the  seeds  are  ripe,  when  they  take  on  bright  colors, 
are  often  fragrant,  and  their  pulp  becomes  agreeable  to  the 
faste,  with  the  evident  design  of  attracting  those  animals 
which  may  aid  in  scattering  the  seeds. 

Small  seeds  are  often  carried  from  place  to  place  while 
embedded  in  the  mud  clinging  to  the  feet  of  birds  and  other 
animals ;  thus  Darwin  found  that  eighty-two  seeds  germi- 
nated from  the  mud  taken  from  the  feet  of  a  single  par- 
tridge. The  small  floating  seeds  of  water  plants  often 
cling  to  water  fowl  as  they  rise  for  flight,  and  are  carried 
to  other  waters.  Those  birds  which  are  able  to  sustain 
swift  and  prolonged  flight  must  be  particularly  efficient  in 
scattering  seeds  over  broad  areas.  Pigeons  and  cranes, 
for  instance,  can  fly  about  forty  miles  per  hour,  and  swal- 
lows and  peregrine  falcons  can  cover  a  hundred  miles  in  the 
same  length  of  time. 

148.  Dispersion  by  Other  Animals.  —  Seeds  of  various 
plants  are  carried  away  and  stored  by  squirrels  and  other 
animals.     Most  of  these  seeds  are  doubtless  eaten,   but 
some  of  them  are  dropped  in  transit.     In  such  cases  the 
service  of  carriage  seems  to  be  dearly  paid,  but  we  may  be 
sure   the  expense  is  not   unwarranted,  since   nut-bearing 
trees  and  shrubs  have  been  able  to  maintain  themselves 


216  Introduction  to  Botany. 

successfully  in  competition  with  other  plants.  The  acorns, 
which,  in  spite  of  their  astringent  taste,  are  palatable  to 
many  nut-loving  animals,  are  often  carried  away  by  them ; 
and  they  are  also  stored  by  woodpeckers  for  the  sake  of 
the  insect  larvae  which  frequently  occur  in  them.  On 
account  of  their  bulk  and  weight,  the  acorns  are  doubtless 
occasionally  dropped  to  the  ground,  and  eventually  suc- 
ceed in  becoming  oak  trees. 

Hooks,  barbs,  and  sticky  glandular  hairs  for  clinging  to 
passing  animals  are  frequently  found  on  the  fruits  of  many 
families  of  plants  (see  //, /,  k,  m,  and  c,  Fig.  127).  Every 
one  is  familiar  with  the  fruits  of  the  cocklebur  arid  burdock, 
which  cling  in  great  numbers  to  the  tails  and  legs  of  cattle 
and  horses  ;  and  the  clinging  qualities  of  the  fruits  of  black 
snakeroot,  beggar-ticks,  and  bur-grass  are  too  familiar  to 
need  more  than  passing  mention.  In  Mentzelia,  the  leaves, 
stems,  and  fruits,  are  covered  with  anchor-like  hairs  which 
become  fastened  to  garments  or  to  animals  so  tenaciously 
that  large  portions  of  the  plant  may  be  broken  off  and 
carried  away  at  once. 

149.  Dispersion  by  Water. — The  nut-like  fruits  of  the 
yellow  water  lily,  Nelumbo  lutea,  are  borne  in  top-shaped 
receptacles  which  are  at  first  upright,  but,  as  the  fruits 
ripen,  bend  downward  so  that  the  nuts  drop  out  or  are 
shaken  out  by  the  wind,  and  sink  at  once  to  the  bottom  of 
the  water  (Fig.  69).  Later  in  the  season  the  receptacles 
break  away  from  their  dry  stalks  and  float  about  on  the 
water,  carrying  with  them  the  few  nuts  which  are  still  held 
captive.  In  this  way  a  considerable  distance  from  the 
parent  plant  may  have  been  traversed  by  the  time  the  re- 
ceptacles have  become  sufficiently  softened  to  set  the 
remaining  nuts  free. 

The  fruits    and   seeds  of  many  genera  of   water  and 


Dispersion  of  Fruits  and  Seeds.  217 

marsh  plants  are  able  to  keep  afloat  for  a  long  time 
and  become  scattered  about  by  the  wind,  finally  sinking 
and  taking  root  in  the  mud.  The  fruits  of  the  cocoa- 
nut  and  other  palms  may  float  for  a  long  time  in  the  sea 
water,  and  are  still  able  to  germinate  after  having  been 
cast  up  on  far-distant  coasts. 

These  few  examples  will  serve  to  introduce  the  student 
to  the  almost  endless  variety  of  devices  for  dispersing 
seeds  and  fruits,  examples  of  which  he  can  readily  find  at 
the  proper  season. 


CHAPTER   X. 
STUDIES  OF  SELECTED  SPERMATOPHYTES. 

In  Chapter  VIII  general  directions  are  given  for  the 
study  of  flowers.  The  studies  which  follow  are  intended 
to  show  how  in  a  course  of  limited  time  certain  plants  may 
be  selected  to  bring  out  facts  of  particular  interest  regard- 
ing the  structure,  behavior,  and  relationship  of  plants.  In 
this  work  Kerner  and  Oliver's  "  Natural  History  of  Plants  " 
and  M tiller's  "  Fertilization  of  Flowers  "  are  most  useful 
books  of  reference. 

Naias  flexilis. 

This  plant  flowers  in  summer,  and  material  should  be 
gathered  then  and  kept  in  formalin  for  class  use. 

The  flowers  are  of  special  interest  on  account  of  their 
great  simplicity.  There  are  no  devices  to  secure  pollina- 
tion by  means  of  insects,  for  the  plant  is  entirely  submerged, 
and  rooted,  and  pollen  is  carried  to  the  stigmas  by  water 
currents.  In  this  genus  the  flowers  are  monoecious  or 
dioecious.  The  staminate  flower  consists  of  a  single  sta- 
men terminating  the  floral  axis,  surrounded  by  a  hyaline 
membrane,  and  this  in  turn  by  a  tubular  leaf,  both  of 
which  constitute  a  double  perianth.  The  pistillate  flower 
consists  of  a  single*  ovule  having  the  two  ovular  coats 
ordinarily  found,  and  an  enveloping  leaf  which  may  be 
considered  as  a  carpel. 

Draw  staminate  and  pistillate  flowers  as  seen  under  a 
hand  lens. 

218 


Studies  of  Selected  Spermatophytes.          219 

The  form  of  the  plant  is  interesting,  since  it  is  plainly 
adapted  to  its  submerged  habitat  (see  page  323).  Take 
fresh  plants  from  water  and  note  how  quickly  they  dry  up. 
The  lack  of  a  waterproof  epidermis  probably  enables  this 
plant  to  absorb  gases  in  solution  throughout  its  surface. 

Do  the  seeds  float  when  ripe,  or  sink  at  once  to  the 
bottom  ? 

This  is  apparently  one  of  the  lowest  of  the  Monocotyle- 
dons. Its  simple  staminate  and  pistillate  flowers  remind 
one  of  the  sporangia  of  Pteridophytes,  and  it  seems  to  be 
on  the  direct  line  of  ascent  from  Pteridophytes  to  Sperma- 
tophytes. The  evidence,  however,  is  not  sufficient  for  a 
definite  conclusion. 

Arisaema  triphyllum. 

Make  a  drawing  to  show  the  habit  of  the  entire  plant. 
What  terms  would  you  apply  to  the  leaves  as  to  their 
habit  and  form  ?  Are  they  simple  or  compound,  radicle  or 
cauline  ?  (See  Glossary.)  The  enlarged  underground  part 
is  a  corm  stored  with  reserve  food. 

The  inflorescence  is  unique.  The  slender,  naked  pedun- 
cle is  called  a  scape.  The  leaf-like  envelope  of  the  inflores- 
cence, funnel-shaped  below,  overarching  above,  is  termed 
a  spathe.  The  fleshy  floral  axis  inclosed  in  the  spathe  is 
called  a  spadix. 

The  flowers  are  very  simple  and  destitute  of  a  perianth. 
A  single  staminate  flower  consists  of  four  stamens,  and  a 
pistillate  flower  of  a  single  pistil.  Note  whether  they  are 
monoecious  or  dioecious,  proterandrous  or  proterogynous 
(see  Glossary). 

Make  a  drawing  of  an  inflorescence  with  the  spathe  cut 
away  on  one  side  to  reveal  the  interior.  Halve  a  pistil 
longitudinally  and  draw  the  ovules  in  position.  Draw  a 


220  Introduction  to  Botany. 

stamen  on  a  large  scale,  showing  the  manner  of  the  de- 
hiscence  of  the  anthers.  Draw  a  stigma  on  a  large  scale, 
showing  the  character  of  its  surface. 

Of  what  use  is  the  spathe  ?  Note  the  behavior  of  in- 
sects while  visiting  the  flowers.  Can  you  see  any  use  for 
the  sterile  upper  part  of  the  spadix  ?  Can  it,  among  other 
uses,  serve  the  attractive  function  of  a  corolla? 

The  student  will  find  it  interesting  to  observe  the  be- 
havior of  this  plant  throughout  the  season.  Examine 
plants  in  their  natural  habitat,  and  find  answers  to  the  fol- 
lowing questions :  What  becomes  of  the  spathe  and  sterile 
portion  of  the  spadix  ?  What  kind  of  fruit  does  the  ripened 
pistil  become  ?  When  and  in  what  way  do  the  seeds  be- 
come planted  in  nature  ?  At  what  time  of  the  year  do  the 
leaves  wither  away  ?  After  the  above-ground  parts  have 
withered  and  the  corm  has  entered  into  its  winter  rest,  can 
the  inflorescence  and  leaves  of  the  following  season  already 
be  found  in  an  embryonic  condition  in  the  apical  bud  of 
the  corm  ? 

Cut  the  corm  in  two  and  put  a  drop  of  iodine  on  the  sur- 
face. Does  a  purple  color  ensue,  indicating  starch  as  re- 
serve food  ?  The  corm  contains  a  very  acrid  substance. 
In  tasting  it  only  a  very  small  piece  should  be  placed  for  a 
moment  on  the  tongue,  for  if  much  is  put  into  the  mouth 
and  chewed  the  result  is  exceedingly  painful.  This  acrid 
substance  is  doubtless  a  protection  against  the  depredation 
of  animals,  for  when  it,  being  volatile,  has  been  driven  out 
by  boiling  or  drying,  the  corms  are  found  to  be  edible. 
Exceedingly  minute  and  sharp  crystals  of  calcium  oxalate 
occur  abundantly  in  the  corms,  but  they  do  not  cause  the 
pain  when  the  fresh  corms  are  eaten,  as  some  have 
thought. 

If  obtainable,  study  Arisczma  dracontium  and  note  the 


Studies  of  Selected  Spermatophytes.          221 

points  of  dissimilarity  which  cause  these  two  Arisamas  to 
be  classed  as  different  species. 

Erythronium  albidum  (or  other  species). 

Make  a  diagram  of  the  flower,  following  the  general 
directions  on  pages  148-151.  Make  a  drawing  to  show  the 
habit  of  the  entire  plant,  including  the  bulb  and  roots. 
How  deep  does  the  bulb  lie  in  the  ground  ?  How  close  to 
the  ground  do  the  leaves  originate  ?  What  is  the  light 
relation  of  the  leaves  ?  Do  both  sides  of  the  leaf  receive 
the  light  energy  about  equally  ?  How  early  in  the  spring 
do  the  leaves  appear  ?  What  advantages  do  you  see  in 
the  very  early  development  of  this  plant  ?  In  its  chosen 
habitat  is  it  at  a  disadvantage  later  in  the  season  ?  Is  it 
apt  to  be  much  shaded  by  other  plants  ?  Make  observa- 
tions in  the  field  to  determine  how  leaves  and  flowers  come 
through  the  ground.  Is  the  flower  upright  or  in  a  nodding 
position  when  it  first  appears  ?  Does  the  flower  open  as 
soon  as  it  appears  ?  Of  what  use  is  the  nodding  position 
of  the  flower  ?  Do  insects  visit  the  flowers,  and  if  so  see 
whether  they  appear  to  be  in  quest  of  pollen  or  nectar. 
Can  you  find  nectar  and  nectaries  ?  In  what  ways  are 
nectar  and  pollen  protected  from  the  rain  ?  At  what  time 
in  the  development  of  the  flower  do  the  anthers  dehisce  ? 
Are  the  flowers  at  all  proterogynous  or  proterandrous  ? 
Do  the  anthers  touch  the  stigmas,  or  could  self  pollen  fall 
upon  them  ? 

Note  the  further  course  of  the  plant  through  the  season. 
Do  many  seeds  mature  in  the  capsule  ?  How  are  the  seeds 
scattered  ?  When  do  the  leaves  ripen  and  wither  away  ? 

The  buds  of  Erythronium  Americanum  and  Erythronium 
albidum  are  each  successive  year  formed  deeper  in  the 
ground  by  means  of  an  offshoot  which  bears  a  new  bulb  at 


222  Introduction  to  Botany. 

its  end.  Erythronium  mesochorium  does  not  produce  off- 
shoots, but  each  year  a  new  bulb  is  formed  which  pushes 
down  a  little  below  the  parent  bulb  within  which  it  remains 
inclosed,  so  that  the  scars  of  last  year's  roots  may  be  found 
a  little  higher  than  the  new  roots  of  the  current  season. 

After  the  plant  has  reached  the  age  of  flowering  the 
rudiments  of  next  year's  leaves  and  flowers  are  already 
formed  in  the  bulb  before  the  leaves  of  the  current  season 
ripen  and  wither  away.  With  plenty  of  food  stored  about 
them  in  the  thick  coats  of  the  bulb  the  young  leaves  and 
flowers  are  able  to  unfold  quickly  in  the  first  days  of  spring. 
The  advantage  of  an  early  start  in  the  spring  is  evident  for 
a  low  plant  whose  habitat  is  grassland,  where  it  is  in 
danger  of  being  browsed  after  the  grasses  appear,  or  wood- 
land, where  the  foliage  of  trees  shuts  out  the  light. 

The  way  in  which  the  two  leaves  enfold  and  protect  the 
flower  bud,  while  the  hard  tip  of  the  outer  leaf  breaks  a 
way  through  the  ground,  is  admirable. 

Sprengel  says  of  the  European  species,  Erythronium 
dens-canis,  that  the  thin  basal  part  of  the  ovary  secretes 
the  nectar,  the  inner  perianth  segments  having  two  auricles 
at  the  base  of  each,  between  which  and  the  nectary  the 
nectar  is  conserved.  Loew  and  Briquet  conclude  that 
the  nectar  is  secreted  by  the  lower  part  of  the  perianth 
segments  below  the  auricles.  See  how  the  species  in  hand 
agrees  with  these  statements. 

The  hanging  position  of  the  flower  seems  to  unfit  it  for 
self  pollination  or  cross  pollination  by  wind.  The  coloration 
of  the  perianth  and  the  secretion  of  nectar  point  to  insects 
as  agents  for  cross  pollination.  Bees  are  known  to  be 
frequent  visitors. 

The  Erythronium  s  are  excellent  for  showing  the  main 
characteristics  of  the  lily  family.  Other  genera  should  be 


Studies  of  Selected  Spermatophytes.         223 

studied  to  show  the  range  of  variations  within  the  family, 
and  on  what  grounds  the  members  of  a  family  are  grouped 
into  genera.  Among  cultivated  plants,  hyacinth,  tulip, 
Yucca,  and  lily,  and  of  wild  flowers  some  species  of  Allium, 
Nothoscordum,  Polygonatum,  and  Camassia  might  be 
studied. 

Most  of  the  flowers  of  the  lily  family  allure  insects  by 
means  of  pollen  or  nectar,  or  both,  and  by  their  fragrance  or 
bright  colors.  Where  the  flowers  are  small,  they  are  often 
massed  in  a  more  or  less  compact  inflorescence  for  a  greater 
color  effect,  as  in  the  case  of  hyacinth  and  Camassia. 
Frequently  cross  pollination  is  assisted  by  proterandry  or 
proterogyny.  The  Yucca  is  one  of  the  most  interesting 
members  of  the  lily  family  in  the  method  of  its  cross  polli- 
nation (see  page  196). 

Hypoxis  erecta. 

Make  diagrams  of  the  flower.  In  what  essential  respects 
does  this  flower  differ  from  that  of  Erythronium  ?  What 
evidence  of  relationship  do  you  find  ?  In  what  way  does 
the  flower  bid  for  insect  visits  ?  Is  there  any  device  to 
prevent  self  pollination  ?  Do  the  anthers  stand  at  the 
right  height  to  accomplish  self  pollination  ?  Do  the  anthers 
and  stigmas  of  one  flower  mature  at  the  same  time  ?  Could 
self  pollination  take  place  in  a  bud  or  in  a  withered  flower  ? 

Sisyrinchium  angustifolium. 

Make  conventional  diagrams  of  the  flower.  Examine 
both  buds  and  flowers  to  see  whether  proterandry  or  pro- 
terogyny exists.  At  what  age  of  the  flower  do  the  anthers 
dehisce  ?  Can  self  pollen  reach  the  stigmas  at  any  time 
while  the  flower  persists?  Note  how  the  styles  and  stigmas 
change  as  the  flower  advances  from  bud  to  maturity. 

Make  observations  in  the  field  to  note  how  long  a  flower 


224  Introduction  to  Botany. 

remains  open  and  what  sorts  of  insects  visit  it.  What  part 
of  this  plant  do  you  find  to  be  perennial?  Note  the  origin 
and  arrangement  of  the  leaves. 

Compare  this  plant  with  Erythronium,  noting  in  what 
respects  the  flowers  differ  so  that  they  are  not  classed  in 
the  same  family,  and  in  what  respects  they  seem  to  be 
related.  Which  flower  would  you  say  is  probably  the  more 
primitive  ?  In  what  ways  is  this  flower  farther  removed 
than  Hypoxis  from  the  lilies  ?  Make  on  one  page  longi- 
tudinal diagrams  of  the  flowers  of  Erythronium,  Hypoxis, 
and  Sisyrinchium,  and  refer  to  them  in  a  brief  discussion  of 
the  essential  characteristics  of  the  families  to  which  they 
belong. 

Iris  Germanica  (or  other  species). 

Show  with  a  simple  outline  drawing  the  habit  of  the 
whole  plant.  What  evidence  do  you  find  to  indicate  that 
the  thick  underground  part  (rhizome)  is  a  stem  ?  Does  this 
part  increase  in  size  from  year  to  year  ?  What  method  of 
growth  has  the  above-ground  leaf -bearing  stem?  (See 
diagrams  on  page  in.)  The  leaves  are  called  equitant 
(Latin  equitans,  riding),  because  the  outer  are  astride  the 
inner.  Can  you  see  any  advantage  in  this  habit  in  respect 
to  protection  or  strength,  or  in  any  other  way  ? 

The  flower  is  adapted  in  a  unique  way  to  secure  cross 
pollination  by  means  of  insects,  particularly  bees.  The  use 
of  the  specific  positions  and  forms  of  the  parts  will  become 
more  apparent  after  the  student  has  seen  bees  gathering 
the  nectar.  By  observation  get  information  about  the 
following  questions :  Where  does  the  bee  alight  on  the 
flower  ?  Where  is  the  nectary  ?  What  does  the  bee  do  to 
get  the  nectar  ?  How  long  must  be  the  tongue  of  the  bee 
to  empty  the  nectary  ?  (See  description  of  the  mouth  parts 


Studies  of  Selected  Spermatophytes.          225 

of  the  bee  on  page  185.)  Can  other  insects  than  bees 
gather  the  nectar  ?  Would  introrse  anthers  serve  as  well 
as  extrorse  anthers  in  this  flower  ?  How  are  pollen  and 
nectar  protected  from  the  rain  ?  Are  there  specially 
colored  parts  which  might  serve  to  guide  insects  to  the 
nectar  ?  Show  in  a  longitudinal  diagram  how  a  bee  would 
necessarily  become  dusted  over  with  pollen,  how  the 
adjacent  stigma  is  prevented  from  receiving  it,  and  how  on 
entering  another  flower  the  stigma  is  quite  certain  to 
become  pollinated. 

Let  the  student  see  what  he  can  add  to  or  correct  in  the 
following  quotation  from  Sprengel's  book  (see  the  account 
of  his  book  on  page  172):  "  Suppose  now  that  a  bumble- 
bee becomes  aware  of  a  distant  Iris  xiphium  which  it  has 
not  yet  seen ;  it  flies  to  the  flower,  attracted  by  its  exquisite 
qualities.  When  near  to  the  flower  the  bee  sees  that  it 
is  indeed  mostly  violet,  but  that  those  three  parts  which 
most  project  'are  blue  and  have  a  beautiful  yellow  spot  in 
the  middle.  So  these  three  parts  attract  the  special  atten- 
tion of  the  bee,  not  only  on  account  of  the  afore-mentioned 
facts,  but  also  because  it  finds  they  are  exactly  the  places 
upon  which  it  can  alight ;  therefore  it  comes  down  upon 
one  of  these  parts  nearest  to  it.  Now  since  the  arched 
sepal  lies  close  against  the  style  these  appear  to  be  a 
single  piece ;  but  since  the  bee  knows  the  significance  of 
the  yellow  spot,  —  namely,  that  it  indicates  the  place  where 
it  must  enter  the  flower, —  it  pays  no  heed  to  that  appear- 
ance but  works  itself  in  between  the  style  and  sepal. 

"  Now  nature,  who  found  it  necessary  to  close  the  flower 
so  that  no  raindrop  could  run  into  the  nectary,  has  in  this 
case  so  arranged  it  that  the  trouble  to  the  bee  is  somewhat 
lessened ;  namely,  the  style  is  stiff  and  immovable  while  the 
sepal  may  be  pressed  downward  easily,  springing  elasti- 


226  Introduction  to  Botany. 

cally  back  again,  however,  as  soon  as  it  is  set  free.  Conse- 
quently the  weight  of  the  bee  helps  it  in  creeping  in,  since 
it  assists  in  pressing  down  the  sepal.  If.  one  consider  the 
case  reversed,  —  namely,  that  the  sepal  could  not  be  pressed 
down  while  the  style  could  be  bent  upward,  —  then  the  bee 
would  have  more  trouble,  for  its  weight  would  be  of  no 
help  and  it  would  need  its  whole  strength  to  press  back 
the  style.  Now  when  the  bee  has  crept  through  the 
entrance,  the  sepal  again  springs  upward  and  the  space 
between  it  and  the  style  becomes  less,  as  it  was  when  the 
bee  crept  in.  Then,  when  directed  by  the  inner  part  of 
the  nectar  guide,  it  creeps  down  to  the  nectary,  the  sepal 
presses  the  bee  against  the  style,  consequently  against  the 
anther  lying  close  to  this,  and  so  the  bee  rubs  the  pollen 
clean  off  with  its  hairy  back.  After  it  has  removed  with 
outstretched  tongue  the  nectar  obtainable  here,  the  bee 
backs  upward  and  out  of  the  flower.  In  doing  this  it  is 
pressed  by  the  sepal  against  the  stigma  lobe  (which  occurs 
on  the  style  where  the  sepal  is  close  to  it),  however  not 
against  its  upper  but  its  under  side,  and  therefore  without 
consequence  to  pollination.  After  the  bee  has  crept  from 
this  third  part  of  the  flower  it  flies  to  one  of  the  remaining 
two.  In  creeping  in  it  is  pressed  by  the  sepal  against  the 
style  so  that  it  rubs  hard  against  the  stigma  lobe  with  its 
back,  and  thus  it  transfers  the  pollen  from  its  back  to  the 
upper  surface  of  the  stigma  lobe,  which  is  the  truly  stig- 
matic  part,  and  fertilizes  the  second  third  of  the  flower, 
or  that  cell  of  the  ovary  which  corresponds  to  this  third. 
In  this  manner  the  bee  flies  from  one  third  of  the  flower 
to  another,  and  from  one  flower  to  another,  and  fertilizes 
them  with  the  pollen  which  it  has  taken  from  the  third  or 
from  the  flower  last  visited." 

Since  Sprengel's  observations  were  made  it  has  been 


Studies  of  Selected  Spermatophytes.          227 

found  that- other  wild  bees  of  smaller  size  are  on  the  whole 
more  efficient  than  the  bumble-bee  in  pollinating  the  Iris. 
Butterflies  sometimes  visit  these  flowers ;  but  since  they  sip 
the  nectar  without  bodily  entering  the  flower,  they  perform 
no  service.  Certain  beetles  have  been  found  to  pierce  the 
nectary  from  the  outside  so  that  the  nectar  flows  out  and 
is  wasted.  Such  insects  may  be  looked  upon  as  robbers. 
Many  other  flowers  besides  the  Iris  suffer  depredations  of 
this  kind. 

Compare  the  flower  of  the  Iris  with  that  of  Sisyrinchium 
or  Nemastylis,  and  write  an  account  of  the  modifications 
from  these  simpler  types  which  the  Iris  has  undergone, 
specially  adapting  it  to  cross  pollination  by  bees.  The 
account  should  be  illustrated  by  simple  diagrams  clearly 
showing  the  main  facts. 

Cypripedium  pubescens  (or  other  species). 

Make  drawings  of  the  flower  and  dissected  parts  from 
the  best  points  of  view  to  clear  up  the  following  points : 
The  number  and  form  of  the  sepals  and  petals ;  the  form 
of  the  stamens  and  pistil  and  their  position  relative  to  the 
other  parts ;  where  insects  (small  bees  in  particular)  enter 
the  flower  and  where  they  leave  it.  How,  on  leaving  the 
flower,  bees  collect  the  sticky  pollen  on  the  upper  part  of 
their  bodies ;  and  how  after  this,  on  leaving  another  flower, 
they  leave  this  pollen  on  its  stigmas  and  then  gather 
another  load  of  pollen. 

Why  do  not  insects  leave  the  flower  by  the  same  open- 
ing through  which  they  enter  it  ?  Find  the  nectar-secreting 
hairs  at  the  base  of  the  large  hollow  petal  termed  the  lip. 
Would  the  other  two  petals  and  the  sepals  probably  serve 
in  attracting  insects  ?  Is  the  nectar  protected  from  the 
rain  ?  By  what  devices  is  the  pollen  protected  against 


228  Introduction  to  Botany. 

waste  ?  Has  the  flower  an  odor  that  we  can  perceive  ?  (See 
page  182  about  the  sense  of  smell  in  insects.)  Describe 
the  color  plan  in  this  flower. 

Study  Cypripedium  in  its  native  habitat.  Is  it  common 
or  of  infrequent  occurrence  ?  Can  you  see  reasons  for 
what  you  find  in  this  regard  ?  Tie  a  string  about  the  base 
of  a  newly  opened  flower  to  mark  it,  and  note  how  many 
days  the  flower  lasts.  Note  what  insects  visit  the  flower 
and  whether  their  visits  are  frequent,  and  watch  them 
enter  and  leave  the  flower.  Note  what  per  cent  of  the 
flowers  become  fertilized  and  produce  seeds. 

The  Orchidaceae,  to  which  family  Cypripedium  belongs, 
show  marked  affinities  to  the  Liliaceae,  Amaryllidaceae, 
and  Iridaceae  (see  studies  of  Erythronium,  Hypoxis, 
Sisyrinchium,  and  Iris).  Comparing  the  flower  of  Cypri- 
pedium with  that  of  a  lily,  we  find  that  they  are  similar  in 
having  three  outer  and  three  inner  perianth  parts,  and 
three  carpels  composing  the  pistil ;  but  we  find  that  the 
ovary  of  the  Orchidaceae  is  inferior,  the  nipper  half  of  the 
flower  is  unlike  the  lower  half,  the  sepals  and  petals  are 
irregular,  and  the  stamens  are  reduced  in  number  and 
apparently  joined  to  the  style.  The  different  genera  of 
the  family  show  marked  specialization,  of  the  flower  to 
secure  cross  pollination  by  insects  (see  -  description  of 
Catasetum  on  page  190).  In  Cypripedium  the  lower  petal 
or  lip  (morphologically  the  upper  petal  but  turned  down- 
ward by  a  twist  in  the  ovary)  forms  an  overarched  cavity 
into  which  the  insect  must  go  to  secure  the  nectar.  While 
the  insect  very  naturally  enters  the  cavity  through  the  large 
opening  on  top,  it  finds  itself  prevented  from  going  out  that 
way  by  the  dome-like  form  of  the  upper  part.  Two  rela- 
tively small  openings  on  either  side  of  the  united  style 
and  stamens  do  not  present  this  difficulty,  and  the  anthers 


Studies  of  Selected  Spermatophytes.          229 

and  stigmas  are  so  placed  that,  as  the  insect  goes  out 
through  one  of  these,  pollen  is  rubbed  off  on  the  upper 
part  of  its  body,  and  afterward,  on  leaving  another  flower, 
this  pollen  is  left  on  the  stigmas  and  a  new  supply  is 
removed.  The  device  to  secure  cross  pollination  here 
worked  out  is  admirable  for  its  simplicity  and  efficiency. 
We  wonder  why  this  plant,  and  orchids  in  general,  do  not 
occur  more  commonly,  since  cross  pollination  has  been  so 
well  provided  for  by  them,  and  a  vigorous  brood  is  in  con- 
sequence to  be  expected.  It  will  be  worth  while  in  fol- 
lowing up  this  question  to  observe  whether  the  necessary 
insect  visits  actually  take  place.  The  flowers  of  Cypripe- 
dium  insigne  are  said  to  last  forty  days  and  those  of 
Cypripedium  villosum  seventy  days.  Does  this  long  life 
of  the  flower  seem  to  indicate  uncertainty  on  the  part  of 
insect  visits  ?  After  fertilization  has  been  accomplished 
we  find  that  the  seeds  resulting  are  numerous  and  very 
minute.  The  large  number  of  course  increases  the  chance 
of  offspring,  but  the  diminutive  size  of  the  seeds  must 
result  in  great  loss  before  and  during  germination.  The 
student  can  think  out  for  himself  in  what  ways  loss  would 
be  likely  to  occur. 

Salix.     (Obtainable  species.) 

What  sort  of  habitat  do  the  willows  prefer  ?  Note  the 
form  of  the  willow,  its  habit  of  branching,  and  the  char- 
acter of  its  branches.  Cut  off  a  small  willow  branch  and 
place  it  in  a  jar  of  water  in  a  warm  room,  and  note  how 
adventitious  roots  are  formed  after  a  time.  The  branches 
of  some  willows  are  quite  brittle,  and  falling  off  frequently 
become  rooted  in  the  mud,  and  in  this  way  multiplication 
may  take  place.  How  early  in  the  spring  do  the  leaves 
and  flowers  appear?  Which  appear  first?  The  flowers 


230  Introduction  to  Botany. 

are  dioecious.  Do  both  kinds  appear  at  the  same  time  ? 
Can  the  pollen  be  blown  about  readily  by  the  wind,  or  is  it 
sticky,  so  as  to  require  the  aid  of  insects,  in  pollination  ? 

What  is  the  nature  of  the  stigma  ?  Do  both  staminate 
and  pistillate  flowers  secrete  nectar  ?  Prove  the  following 
statement  from  Sprengel :  "  Whoever  examines  the  pistil- 
late flowers  of  willows  will  find  a  drop  of  nectar  on  their 
nectaries."  Draw  a  staminate  and  a  pistillate  inflorescence 
showing  the  form  of  the  bracts  subtending  the  flowers. 
Draw  a  staminate  and  a  pistillate  flower  from  the  best 
point  of  view  to  show  all  of  the  parts.  Make  a  drawing 
of  a  mature  fruit,  showing  how  the  capsule  breaks  open 
and  how  the  seeds  are  disseminated. 

Populus  monilif era  (or  other  species) . 

Draw  a  branch  showing  the  difference  between  flower 
buds  and  leaf  buds  as  to  position,  form,  and  size.  Note 
how  the  buds  are  protected.  Draw  a  leaf  in  position  on 
the  branch,  showing  its  light  relation,  —  that  is,  its  position 
relative  to  the  strongest  incident  light.  Where  do  these 
trees  most  abound  ?  Draw  staminate  and  pistillate  inflo- 
rescences, showing  their  position  with  reference  to  the  verti- 
cal. Show  the  forms  of  the  scales  subtending  the  flowers. 
Draw  staminate  and  pistillate  flowers  from  the  best  point 
of  view  to  show  the  number,  form,  and  position  of  the 
parts.  Is  the  pollen  sticky,  or  is  it  dry  and  easily  carried 
about  by  the  wind  ?  Draw  the  stigmas  on  a  large  scale, 
and  decide  whether  they  are  well  adapted  to  catch  and 
hold  pollen  wafted  to  them  by  the  wind.  Note  whether 
insects  visit  both  pistillate  and  staminate  flowers.  When 
the  capsules  are  ripe,  notice  how  they  break  open,  how  the 
hairs  on  the  seeds  spread  apart,  and  how  the  seeds  are 
scattered. 


Studies  of  Selected  Spermatophytes.          231 

Now  compare  the  poplars  and  willows  and  tabulate  their 
similarities  and  dissimilarities  so  as  to  bring  out  the  grounds 
for  classifying  them  in  the  same  family  but  in  different 
genera. 

Ranunculus  abortivus. 

State  the  character  of  the  habitat  in  which  this  plant 
grows.  Draw  its  different  kinds  of  leaves  from  base  to 
apex,  including  the  leaves  of  the  involucre  subtending  the 
flowers.  What  advantage  is  given  to  the  lower  leaves  by 
their  long  petioles  ?  Draw  a  flower  so  as  to  show  clearly 
sepals,  petals,  stamens,  and  pistils.  Study  a  longitudinal  sec- 
tion through  the  center  of  a  flower,  and  make  a  longitudinal 
diagram  according  to  the  directions  on  page  153.  Do  the 
anthers  all  dehisce  at  the  same  time  ?  Do  stigmas  and 
anthers  mature  at  the  same  time  ?  Can  nectar  be  found  ? 
Is  the  pollen  of  a  nature  to  be  carried  by  the  wind? 
Would  self  pollination  probably  take  place  ?  Study  a 
species  of  Myosurus  in  the  same  manner.  How  does  it 
differ  from,  and  what  has  it  in  common  with  Ranunculus  ? 
What  advantages  do  you  see  in  the  elongation  of  that  part 
of  the  receptacle  which  bears  the  pistils  ?  Would  this 
habit  insure  the  self  pollination  of  all  the  pistils  ? 

Delphinium.     (Obtainable  species.) 

Note  the  habitat,  habit,  and '  size  of  the  plant.  Draw  a 
typical  leaf.  Draw  an  inflorescence  showing  correctly  the 
position  of  the  flowers  and  the  direction  of  the  spur.  Dis- 
sect a  flower  and  identify  the  different  parts.  Discover 
what  purposes  the  irregularities  in  the  parts  serve.  (For 
suggested  diagram  of  the  flower,  see  Fig.  79.)  Get  a  good 
understanding  of  the  positions  of  the  different  parts  in 
flowers  of  various  ages  from  bud  to  withering  flower. 


232  Introduction  to  Botany. 

Answer  from  observation  the  following  questions  :  How  is 
the  pollen  protected?  Where  is  the  nectar  secreted  and 
stored  up  ?  How  is  the  nectar  protected  from  the  rain  ? 
To  what  sorts  of  insects  is  the  nectar  accessible  ?  Do  the 
anthers  all  discharge  their  pollen  at  the  same  time  ?  What 
positions  do  the  anthers  assume  before  and  after  discharg- 
ing their  pollen  ?  Do  the  anthers  and  stigmas  of  a  flower 
mature  at  the  same  time,  or  does  the  flower  afford  an  ex- 
ample of  proterandry  or  proterogyny  ?  Do  the  styles  and 
stigmas  assume  different  positions  at  different  ages  of  the 
flower  ?  Now  make  three  longitudinal  diagrams,  one  of  a 
newly  opened  flower,  one  of  a  middle-aged  flower,  and  one 
of  a  fading  flower,  showing  the  different  positions  of  the 
stamens  and  styles.  Observe  the  positions  of  insects  in 
visiting  these  flowers.  Do  they  proceed  from  young  to 
older  flowers  of  the  inflorescence  or  vice  versa  ?  What 
order  of  procedure  would  be  best  to  insure  cross  pollina- 
tion between  flowers  of  different  plants?  How  long  must 
the  insect's  proboscis  be  to  reach  the  bottom  of  the  nectary  ? 
In  what  ways  are  these  flowers  adapted  to  attract  insects  ? 

Compare  Delphinium  with  Ranunculus.  What  similari- 
ties have  they  which  warrant  their  classification  in  the 
same  family  ?  What  dissimilarities  compel  a  classification 
in  different  genera  ? 

The  flower  of  the  larkspur  is  of  peculiar  interest  on  ac- 
count of  the  specialization  of  its  parts  for  definite  purposes. 
The  changes  in  the  positions  of  stamens  and  styles  at  dif- 
ferent periods  are  wonderful  exhibitions  of  the  power  of 
movement  of  plant  parts  to  accomplish  specific  results. 

Dicentra  cucullaria. 

What  is  the  habitat  of  this  plant  ?  What  is  *the  char- 
acter of  its  underground  parts  ?  Why  are  the  leaves  called 


Studies  of  Selected  Spermatophytes.         233 

ternately  compound?  Describe  the  leaflets.  What  term 
would  you  apply  to  the  inflorescence?  (See  page  158.) 
Examine  a  bud.  What  sort  of  a  calyx  has  it  ?  Note  what 
becomes  of  the  calyx  about  the  time  when  the  flower 
opens.  Examine  the  interior  of  the  spurs  of  the  subcor- 
date  outer  petals.  Do  they  contain  nectar  ?  Is  the  nectar 
apparently  secreted  by  the  spur  itself,  or  are  there  out- 
growths from  the  stamens  (as  in  the  violet),  which  serve  as 
nectaries  ?  Are  the  flowers  fragrant  ?  Notice  how  the 
two  inner  petals,  united  at  their  apices,  protect  the  anthers 
and  stigmas.  Would  these  petals  be  pushed  aside  by  bees 
in  quest  of  nectar?  Do  they  spring  back  after  being 
pushed  aside  ?  Note  the  actions  of  bees  in  visiting  these 
flowers.  Do  the  anthers  dehisce  while  the  flowers  are 
still  in  bud  ?  As  soon  as  the  pollen  is  discharged,  are  the 
stigmas  ready  to  receive  it  ?  Could  self  pollination  possi- 
bly take  place  ?  Would  it  make  any  difference  in  the 
problem  of  pollination  whether  insects  work  from  the  bot- 
tom of  the  inflorescence  upward  or  vice  versa  ?  Dissect  a 
flower  and  draw  the  different  parts.  Make  longitudinal 
and  cross  diagrams  of  a  flower. 

Corydalis.     (Obtainable  species.) 

Study  according  to  the  outline  for  Dicentra.  Compare 
Dicentra  and  Corydalis.  Why  should  they  not  be  classified 
under  the  same  genus  ? 

Capsella  bursa-pastoris. 

Draw  an  entire  plant,  using  the  symbols  for  leaves, 
flowers,  and  fruits  suggested  on  page  158.  Draw  a  typical 
basal  leaf  and  stem  leaf.  Draw  a  single  flower  showing  a 
combined  side  and  top  view.  Dissect  a  flower  and  draw 
one  of  each  set  of  parts.  Find  the  term  tetrad ynamous  in 
the  glossary.  Can  it  be  applied  to  this  flower  ?  Draw  a 


234  Introduction  to  Botany. 

cross  section  of  the  ovary,  showing  the  attachment  of  the 
ovules.  (It  is  a  good  plan  to  select  a  somewhat  mature 
fruit  for  this  purpose.)  What  are  the  relative  positions  of 
anthers  and  stigmas  ?  Are  stigmas  and  anthers  mature  at 
the  same  time  ?  Is  self  pollination  liable  to  take  place  ? 
Find  the  nectaries.  Is  the  flower  fragrant  ?  When  insects 
visit  these  flowers,  would  they  be  likely  to  cause  self  or 
cross  pollination  ?  Make  a  drawing  showing  how  the 
capsules  break  open,  and  how  the  seeds  become  scattered. 
This  plant  has  become  naturalized  from  Europe.  It 
occurs  in  nearly  all  parts  of  the  world  and  shows  a  great 
aptitude  in  taking  possession  of  waste  places.  It  has  a 
great  advantage  over  most  other  herbaceous  plants  in 
being  able  to  withstand  low  temperatures  and  to  send 
forth  its  leaves  and  flowers  in  the  first  warm  days  of  late 
winter  or  early  spring.  (See  on  page  311  an  account  of 
Cochlearia  belonging  to  the  same  family.)  Watch  for  it  at 
such  times  and  note  how  much  it  is  in  advance  of  other 
plants.  Now  note  down  all  of  the  points  in  its  structure 
and  habits  which  help  to  make  it  a  successful  competitor 
with  most  other  plants  in  all  parts  of  the  world.  (Read 
the  chapter  on  Plants  of  Different  Regions.)  Compare 
other  genera  in  this  family  with  Capsella. 

Prunus  chicasa  (or  other  species). 

Study  the  trees  in  their  native  habitat  at  the  time  of 
blooming.  What  is  the  character  of  the  inflorescence  ? 
At  what  stage  of  development  are  the  leaves  when  the 
tree  is  in  blossom  ?  Tell  the  different  means  by  which 
the  flowers  are  made  conspicuous.  Draw  a  flower  from 
the  point  of  view  which  best  shows  the  form  and  relative 
positions  of  all  the  parts.  What  is  the  position  of  the 
anthers  with  reference  to  the  stigmas  ?  Do  the  anthers 


Studies  of  Selected  Spermatophytes.          235 

all  mature  at  about  the  same  time  ?  Can  self  pollination 
take  place  spontaneously,  or  is  the  aid  of  insects  neces- 
sary ?  Where  is  the  nectary  ?  What  kinds  of  insect 
visitors  do  you  find  ?  Examine  flowers  of  different  ages 
for  exudation  of  nectar.  Make  a  cross  section  of  the 
ovary.  How  many  cells  and  how  many  ovules  do  you 
find?  Make  a  longitudinal  diagram  of  a  flower.  Estimate 
approximately  the  percentage  of  flowers  that  fall  off 
without  forming  fruit.  How  do  you  account  for  the 
facts  ? 

Compare  a  peach  flower  with  that  of  the  plum.  In  both 
cases  what  part  of  the  ovary  forms  the  pulp  of  the  fruit, 
and  what  part  forms  the  stone  ?  What  reasons  do  you  see 
for  classifying  the  plum-  and  peach  in  the  same  genus? 
Compare  the  flower  and  fruit  of  the  apple  with  that  of  the 
plum  and  peach.  What  are  the  reasons  for  classifying 
the  apple  in  the  same  family  with  the  plum  and  peach, 
but  not  in  the  same  genus?  In  what  details  would  the 
plum  flower  need  to  be  modified  to  become  like  the  apple 
flower?  How  does  the  following  statement  agree  with 
what  you  are  able  to  observe :  The  fruit  of  the  apple  is 
composed  of  the  ovary  (the  core)  immersed  in  and  ad- 
hering to  the  fleshy  receptacle.  For  comparison  make  on 
one  page  longitudinal  diagrams  of  the  flowers  and  fruits  of 
the  peach  or  plum  and  apple  and  point  out  the  correspond- 
ing parts  in  flowers  and  fruits. 

Fragaria  Virginiana. 

Draw  the  entire  plant.  What  term  would  you  apply 
to  the  underground  stem  ?  What  term  to  the  leaves  ? 
Describe  the  leaflets  as  to  form,  margin,  texture,  etc. 
Show  by  drawings  how  multiplication  other  than  by  seeds 
takes  place.  Examine  a  patch  of  wild  strawberries  in 


23 6  Introduction  to  Botany. 

bloom.  Are  the  flowers  all  alike?  Are  the  pistils  simple 
or  compound  ?  What  term  would  you  apply  to  the  ripened 
pistil  ?  What  is  the  morphology  of  the  fleshy  part  of  the 
fruit  ?  What  modifications  would  the  ripened  pistil  of  the 
strawberry  have  to  undergo  to  be  like  that  of  the  plum  ? 
Compare  the  flowers  of  strawberry  and  plum.  Why  are 
these  plants  classified  in  the  same  family  ?  Why  not  in 
the  same  genus  ?  What  changes  would  the  flowers  of  the 
plum  need  to  undergo  to  become  like  those  of  the  straw- 
berry ?  How  much  of  the  fruit  of  the  blackberry  is  formed 
by  the  ripened  pistils  ? 

Rosa  Arkansana  (or  other  species). 

Describe  the  habit  of  the  plant.  Draw  an  entire  leaf. 
What  descriptive  terms  would  you  apply  to  it  ?  Are  the 
flower  buds  formed  on  branches  of  the  current  year  or 
on  older  branches  ?  At  what  time  of  day  do  the  flowers 
open  ?  Do  insects  visit  these  flowers  ?  Do  you  find  them 
gathering  nectar  or  pollen  ?  Notice  the  relative  positions 
of  anthers  and  stigmas.  Would  self  pollination  probably 
take  place  ?  Make  a  longitudinal  diagram  of  a  bud  show- 
ing how  the  floral  envelopes  protect  the  inner  parts  and 
how  the  latter  are  packed  in  small  space.  Make  longi- 
tudinal and  cross  diagrams  of  an  open  flower.  Follow 
the  subsequent  development  of  the  fruit.  What  changes 
would  be  necessary  to  make  the  flower  of  the  strawberry 
like  that  of  the  rose?  What  would  be  required  to  make 
the  flower  and  fruit  of  the  rose  like  that  of  the  apple  ? 

The  fruits  of  the  rose  are  eaten  by  birds  and  the  seeds 
scattered  uninjured.  The  bright  color  of  the  ripened 
receptacle  or  "hip"  makes  it  conspicuous  in  fall  and 
winter.  Mice  are  fond  of  the  rose  fruit,  but  since  they 
gnaw  into  and  destroy  the  seeds  they  are  not  useful  in 


Studies  of  Selected  Spermatophytes.          237 

seed  dispersal  as  birds  are.  It  seems,  however,  that  mice 
are  often  deterred  from  climbing  the  bushes  by  the  down- 
ward-pointing prickles,  and  then  eat  only  those  fruits  which 
are  accidentally  broken  off. 

The  rose  family  is  one  of  the  most  important,  since  it 
supplies  our  best  fruits  and  some  of  our  most  beautiful 
flowers.  Write  a  review  of  the  plants  of  this  family  which 
you  have  studied,  embracing  the  following  points :  The  dif- 
ference in  size  and  habit  shown  by  the  various  genera.  The 
different  kinds  of  leaves.  The  divers  forms  and  character 
of  the  receptacles.  The  essential  similarity  of  the  flowers 
of  the  family. 

Astragalus  caryocarpus  (or  other  species,  and  species  of  other 
genera  in  the  same  family). 

Draw  a  leaf.  Is  it  simple,  or  palmately  or  pinnately 
compound  ?  Draw  an  inflorescence  showing  the  position 
in  which  the  flowers  stand  with  reference  to  the  vertical. 
Draw  the  different  kinds  of  petals.  The  upper  petal  is 
called  the  standard  or  vexillum  ;  the  two  lateral  petals  are 
termed  the  wings  or  alee  ;  the  two  united  lower  petals  con- 
stitute the  keel  or  carina.  When  a  bee  visits  one  of  these 
flowers,  it  alights  on  the  wings  and  keel.  Watch  a  flower 
at  such  a  time  to  see  what  transpires.  What  occurs  after 
the  bee  leaves  the  flower  ?  Press  down  upon  the  wings 
and  keel  with  the  finger  tip  or  with  a  pencil  and  note  how 
stigmas  and  anthers  are  exposed.  Notice  what  happens 
after  the  pressure  is  removed.  Study  the  mechanism 
by  which  the  spring-like  action  of  the  wings  and  keel  is 
brought  about.  Now  write  down  the  different  purposes 
fulfilled  by  the  standard,  wings,  and  keel.  Note  the  posi- 
tions of  anthers  and  stigmas  in  bud  and  in  blossoms  of 
different  ages.  Where  is  the  nectar  secreted?  What 


238  Introduction  to  Botany. 

path  must  the  insect's  proboscis  follow  in  reaching  it? 
Note  all  devices  concerned  with  the  protection  of  the 
nectar  and  pollen.  Make  a  cross  diagram  of  the  flower, 
and  in  it  show  accurately  how  the  wings  and  keel  are 
locked  together.  Does  the  form  of  the  calyx  seem  to  have 
any  definite  relation  to  the  peculiarities  of  structure  of  the 
other  parts  ?  Compare  the  flowers  of  the  different  genera 
of  the  family  studied.  Compare  the  different  members  of 
this  family  which  you  have  studied,  as  to  size  and  habit, 
forms  of  leaves,  details  of  floral  structure,  and  character 
of  fruit.  What  features  are  common  to  the  family,  and 
in  what  features  do  you  find  the  greatest  variations  ? 

Oxalis  violacea. 

Draw  an  entire  plant,  including  the  bulb  and  roots. 
(Some  of  the  leaves  may  be  omitted.)  What  term  would 
you  apply  to  the  leaves,  bulb,  and  inflorescence  ?  Note 
how  the  leaflets  are  folded  as  they  emerge  from  the  bud, 
and  notice  the  day  and  night  positions  of  the  mature  leaf- 
lets. Look  for  the  two  forms  of  flowers.  (Read  about 
dimorphic  flowers  on  page  176.)  Make  longitudinal  dia- 
grams showing  exactly  the  positions  of  stamens  and  styles 
in  the  two  forms.  Note  how  the  petals  are  wrapped  in 
the  bud.  At  what  time  of  day  do  the  flowers  open  ? 
After  once  opening,  do  they  close  and  open  again  ?  Note 
the  positions  of  flowers  and  leaves  in  cloudy  and  stormy 
weather.  What  meaning  do  you  attach  to  their  behavior  ? 
Note  the  way  in  which  the  seeds  are  ejected  from  the 
capsules.  Compare  Oxalis  violacea  with  Oxalis  stricta,  or 
other  obtainable  species. 

Acer.     (Obtainable  species.) 

Dissect  an  inflorescence  and  find  how  much  of  it  con- 
stitutes a  single  flower.  Examine  inflorescences  from  dif- 


Studies  of  Selected  Spermatophytes.          239 

f erent  trees  and  find  whether  staminate,  pistillate,  and 
perfect  flowers  occur.  Make  longitudinal  diagrams  of 
the  different  kinds  of  flowers.  Draw  a  stamen  and  a  pistil 
on  a  large  scale  as  seen  under  a  lens.  Study  with  a  lens 
and  show  by  a  drawing  the  position  and  character  of  the 
stigmatic  surface.  Do  insects  visit  these  flowers  ?  Are 
the  maple  flowers  adapted  to  cross  pollination  ?  What  is 
the  advantage  in  this  case  in  having  the  flowers  appear 
before  the  leaves  ?  Follow  the  development  of  the  pistil 
to  the  mature  fruit  and  state  what  changes  the  pistil  under- 
goes in  ripening.  What  part  of  the  pistil  forms  the  wings  ? 
Do  all  of  the  ovules  become  seeds  as  a  rule  ? 

Viola.     (Obtainable  species.) 

Study  all  obtainable  species  of  the  violet.  State  the 
character  of  the  habitat  of  the  different  species  studied. 
Draw  a  typical  leaf.  How  are  the  leaves  rolled  up  in  the 
bud  ?  Draw  a  rootstock.  What  evidence  do  you  find  that 
it  is  morphologically  a  stem  ?  What  is  the  nature  of  the 
roots  ?  Draw  a  flower  in  right  position  with  reference  to 
the  vertical.  Study  the  face  of  a  flower.  Is  there  an 
opening  through  which  an  insect  can  enter  or  thrust  its 
proboscis  ?  Is  pollen  visible  ?  Dissect  a  flower.  What 
part  constitutes  the  spur?  The  horn-like  projections  from 
the  two  lower  stamens  secrete  the  nectar  and  pour  it  into 
the  spur.  Do  you  find  nectar  there  ?  Do  the  anthers 
dehisce  toward  the  outside  or  inside  ?  What  becomes  of 
the  pollen  after  the  anthers  break  open  ?  What  is  the  use 
of  the  scale-like  tips  of  the  stamens  ?  Is  the  stigma  so 
shaped  and  situated  as  to  receive  self  pollen  ?  Sum  up 
those  facts  about  the  flower  which  relate  to  its  pollination. 
How  are  the  pollen  and  nectar  protected  against  waste  ? 
As  the  flower  is  constructed,  would  it  be  just  as  well  for  it 


240  Introduction  to   Botany. 

to  point  directly  upward  or  downward  ?  (We  want  to  find 
out  by  this  question  whether  the  pose  of  the  flower  is  cor- 
related with  its  form  and  construction.)  Draw  the  dif- 
ferent parts  of  a  flower.  Make  cross  and  longitudinal 
diagrams  of  a  flower.  (A  suggested  method  of  treatment 
in  diagraming  a  violet  is  given  on  page  154,  but  the 
student  should  make  each  diagram  accurately  show  the 
characteristics  of  the  species  in  hand.)  Note  that  the  pis- 
til of  the  violet  is  one-celled  but  compound,  as  shown  by 
the  three  placentae.  Study  the  inconspicuous  cleistoga- 
mous  flowers  that  appear  later  on  short  peduncles.  Show 
how  self  pollination  is  accomplished  in  these  flowers.  Do 
the  early  and  conspicuous  or  later  cleistogamous  flowers 
appear  to  be  the  more  fruitful  ?  It  seems  from  a  study  of 
the  violet  that  the  cleistogamous  flowers  are  remarkably 
successful  in  accomplishing  self  fertilization ;  the  evil 
results  which  might  be  expected  to  follow  are  apparently 
kept  from  accumulating  in  the  species  by  the  occurrence 
of  cross  fertilization  in  the  early,  conspicuous  flowers. 

Write  a  short  essay  on  the  genus  Viola,  covering  habitat, 
time  of  blooming,  form  of  plant,  forms  of  leaves,  coloration 
of  flowers,  variations  in  details  of  floral  structure  in  the 
different  species,  relative  fertility  of  conspicuous  and 
cleistogamous  flowers,  aesthetic  considerations. 

Let  the  student  test  his  thoroughness  and  accuracy  by 
comparing  the  results  of  his  work  with  the  following  inter- 
esting account  by  Sprengel  of  his  own  discoveries  relating 
to  the  violet :  — 

"  The  nectar  receptacle  is  the  end  of  the  spur  of  the 
corolla.  At  first  I  could  not  understand  why  in  Viola 
canina  I  should  find  nectar  there  but  not  on  the  nectary ; 
but  finally  I  perceived  that  this  occurs  naturally,  for  the 
end  of  the  spur  has  the  form  of  an  arch  which  curves 


Studies  of  Selected  Spermatophytes.          241 

about  the  drops  of  nectar  excreted  by  the  nectary.  Thus 
it  attracts  the  drops  from  many  sides  and  consequently 
more  powerfully  than  the  nectary  does,  and  the  drops 
of  nectar  must  follow  the  stronger  force  and  flow  from 
the  nectary  into  the  end  of  the  spur.  And  here  from  the 
same  cause  the  nectar  must  remain  and  not  flow  down  and 
out  of  the  corolla  as  it  tends  to  do  on  account  of  its  weight. 
.  .  .  That  the  nectar  is  fully  protected  from  all  injury 
by  the  rain  is  apparent.  Even  if  a  drop  of  rain  should 
get  near  to  the  opening  of  the  spur,  it  could  not  enter ;  but 
in  order  that  it  may  not  even  approach  the  opening  the 
two  middle  petals  have  hairs  just  where  they  can  be 
most  effective.  Thus  when  raindrops  have  fallen  upon 
the  upper  petal  and,  running  down  it,  have  united  into  a 
single  drop,  the  latter  is  arrested  as  soon  as  it  has  reached 
these  hairs.  It  is  therefore  utterly  impossible  for  a  rain- 
drop ever  to  reach  the  nectar.  ...  In  Fig.  13  [in 
Sprengel's  book]  one  sees  the  greater  part  of  the  nectar 
guides  on  the  lowest  petal.  This  figure  and  Fig.  8  show 
how  the  veins  run  a  bit  into  the  opening  of  the  spur. 
Therefore  a  bee  were  as  stupid  as  a  fly  if  it  did  not  know 
how  to  find  the  nectar  as  soon  as  it  has  alighted  on  the 
flower.  Now  how  is  this  violet  pollinated?  In  order 
properly  to  answer  this  question,  which  for  several  years 
was  an  apparently  insolvable  riddle  for  me,  I  must  make 
the  reader  somewhat  more  closely  acquainted  with  this 
flower.  The  five  anthers  surround  the  pistil  and  conceal 
it  so  that  one  sees  no  more  than  the  reflexed  end  of  the 
style.  They  are  not  grown  together  but  touch  one  another 
and  appear  to  be  a  single  body.  The  filaments  are  some- 
what fleshy ;  the  two  lowest  have  each  a  projection  just  as 
fleshy  which  extends  into  the  spur ;  the  ends  of  the  pro- 
jections, as  said,  secrete  the  nectar.  Each  filament  has  an 


242  Introduction  to  Botany. 

anther  consisting  of  two  pollen  sacs  on  its  inner  side  facing 
the  pistil.  Each  stamen  has  at  its  apex  an  appendage 
which  consists  of  a  thin,  dry,  yellow  membrane  having  a 
slight  amount  of  elasticity.  However,  these  appendages 
do  not  merely  lie  side  by  side  around  the  style  as  the 
filaments  do,  but  in  part  over  one  another,  so  that  they 
appear  even  more  like  a  single  body  than  the  filaments  do. 
One  sees  that  the  appendages  of  the  two  lateral  anthers 
are  covered  by  those  of  the  upper  and  two  lowest,  and  that 
the  appendage  of  one  of  the  two  lowest  lies  in  part  upon 
that  of  the  other.  Thus  the  stamens,  together  with  the 
appendages,  have  the  form  of  the  upper  conical  part  of  a 
funnel,  from  the  lower  opening  of  which  the  style  sticks 
out  and  at  the  same  time  completely  fills  and  closes  this 
opening.  The  part  of  this  funnel  which  is  formed  by  the 
filaments  I  propose  to  call  the  upper,  and  that  formed  by 
the  appendages  the  lower  part. 

"The  pollen  revealed  by  the  anthers  after  they  have 
opened  is  of  a  very  peculiar  kind,  for  while  the  pollen  of 
other  nectar-bearing  flowers  clings  somewhat  firmly  and  is 
of  such  a  nature  as  to  be  comparable  to  rather  moist  flour, 
that  it  may  not  be  blown  away  by  the  wind  or  scattered 
when  the  wind  shakes  the  flowers,  the  pollen  of  the  violet, 
on  the  contrary,  is  completely  dry  and  does  not  cling  at  all 
to  the  pollen  sacs  after  they  have  opened.  It  is  thus  like 
the  pollen  of  those  flowers  that  are  pollinated  by  the  wind, 
although  this  agent  is  not  here  employed.  Still  it  is  not 
as  fine  as  the  latter  and  is  more  like  flour  than  like  actual 
pollen.  The  two  pollen  sacs  of  each  filament  have  a 
prominent  border  at  the  upper  end  and  on  the  sides,  but 
not  at  all  below  where  the  appendage  begins.  Thus  the 
dry  pollen  is  hindered  by  nothing  from  falling  from  the 
upper  into  the  lower  part  of  the  funnel.  That  just  this 


Studies  of  Selected  Spermatophytes.          243 

must  happen  can  be  seen  when  the  quality  of  the  pollen  is 
considered,  together  with  the  fact  that  the  flower  is  at  the 
arched  end  of  a  long  stem  and  must  in  consequence  often 
be  shaken  by  the  wind.  Since  the  opening  at  the  lower 
end  of  the  funnel  is  closed  by  the  style,  the  pollen  that  has 
fallen  into  this  part  cannot  escape  through  the  opening. 
One  may  imitate  the  wind  as  best  he  can ;  one  may  blow 
into  the  flower  or  shake  it  ever  so  hard,  provided  the  fun- 
nel is  not  injured  or  pressed  upon  in  so  doing,  and  still  not 
a  grain  of  the  pollen  is  brought  to  light.  Since,  now,  the 
projecting  bent  end  of  the  style  is  the  stigma,  the  arrange- 
ment of  this  flower  must  seem  perfectly  absurd  to  one 
who  knows  about  the  pollination  of  flowers  by  mechanical 
means  only ;  for  all  other  parts  of  the  pistil  become  polli- 
nated, which  does  not  have  the  slightest  influence  upon 
fertilization,  and  precisely  the  stigma  alone,  which  must 
necessarily  be  pollinated  if  fertilization  is  to  follow,  is  ex- 
cluded from  pollination.  If,  then,  we  were  to  conceive  of 
pollination  as  taking  place  solely  by  mechanical  means,  we 
should  have  to  believe  either  that  fertilization  never  takes 
place  in  this  flower,  which,  however,  is  against  the  facts, 
or  that  the  flower,  notwithstanding  its  possession  of  all  the 
parts  required  in  natural  fertilization,  is  fertilized  by  God 
in  an  unnatural  way  and  by  a  miracle,  just  because  its  parts 
are  so  strangely  and  impractically  constructed  and  arranged. 
And  that  is  the  same  as  saying,  as  we  must  think,  that  on 
account  of  the  mistake  which  He  has  made  in  the  construc- 
tion of  this  flower  God  punishes  Himself  by  the  necessity 
of  performing  a  miracle  on  each  successive  individual. 
Now  if  we  are  neither  to  deny  the  existence  of  anything 
that  is,  nor  affirm  the  existence  of  the  impossible,  nothing 
remains  for  us  but  to  resort  to  insects.  And  since  the  bees, 
which,  as  we  have  heard,  visit  this  flower,  have  already  so 


244  Introduction  to  Botany. 

often  done  us  good  service,  it  is  to  be  hoped  that  they  will 
not  desert  us  in  this  extremity  also.  The  end  of  the  style 
is  bent  in  such  a  way  that  it  makes  a  somewhat  sharp 
angle  with  the  style,  but  its  base  is  somewhat  crooked 
and  much  more  slender  than  the  rest.  On  this  account 
it  is  very  easily  lifted  up ;  but  as  soon  as  released  it  falls 
back  into  its  accustomed  position.  Now  when  a  bee 
crawls  upon  the  upper  petal  and  sticks  its  head  into  the 
rather  large  space  between  the  stigma  and  lowest  petal, 
in  order  to  thrust  its  proboscis  into  the  nectar  receptacle, 
it  lifts  with  its  head  the  style,  and  with  it  the  append- 
age of  the  upper  anther.  In  this  way  an  opening  is 
made  in  the  funnel,  through  which  the  pollen  falls  out. 
Thus  the  bee  becomes  dusted  with  the  pollen  and  neces- 
sarily transfers  a  part  of  it  to  the  stigma,  and  in  this  way 
the  pistil  becomes  fertilized.  After  it  has  consumed  the 
nectar  the  bee  crawls  back  again,  and  then  the  style  falls 
back  into  its  accustomed  place,  and  likewise  gradually  the 
appendage  of  the  upper  filament.  Thus  the  opening  of  the 
funnel  gradually  closes,  although  not  so  tight  and  snug  as 
before  the  visit,  probably  because  fertilization  necessarily 
follows  from  the  first  visit. 

"This  method  of  pollination  of  this  flower  discovered 
and  described  by  me  enables  the  reader  to  answer 
various  questions  relating  to  the  structure  of  the  flower 
which  he  would  otherwise  have  to  leave  unanswered.  The 
easier  questions  that  come  up  in  regard  to  the  structure  of 
other  nectariferous  flowers  I  will  not  touch  upon,  for 
example:  Why  the  flower  secretes  nectar,  why  it  has  a 
colored  corolla,  why  it  has  dark  lines  upon  a  light  back- 
ground, why  it  is  possessed  of  an  agreeable  odor,  why  the 
nectar  is  so  well  protected  against  the  rain.  But  I  will 
bring  forward  the  following :  Why  does  the  flower  grow 


Studies  of  Selected  Spermatophytes.          245 

upon  a  long  upright  stem  which,  however,  bends  over 
and  downward  at  its  upper  end  ?  Answer :  First,  in 
order  that  no  raindrop  can  get  at  the  nectar ;  for  if  the 
stem  were  quite  straight  and  the  flower  stood  upright 
in  consequence,  the  end  of  the  spur  where  the  nectar 
occurs  would  be  the  lowest  part  of  the  flower,  and  rain- 
drops which  fall  into  the  flower  would  flow  down  into  the 
spur  and  mix  with  the  nectar  and  spoil  it.  But  since  the 
upper  part  of  the  stem  bends  down,  the  flower  hangs  down  ; 
and  the  end  of  the  spur  is  the  highest  part  of  it,  into  which 
no  raindrop  can  flow.  Second,  in  order  that  when  the 
flower  is  shaken  by  the  wind,  which  must  often  occur  on 
account  of  the  length  of  the  stem,  the  pollen  may  fall  into 
the  lowest  part  of  the  funnel.  If  the  stem  were  straight 
and  the  flower  had  an  upright  position,  the  pollen  would 
fall  into  the  part  of  the  funnel  which  would  then  be  the 
lowest,  that  is,  the  upper  part  formed  by  the  filaments ;  so 
it  would  lie  there  when  a  bee  visits  the  flower,  and  never 
be  brought  upon  the  stigma. 

"Why  does  the  pollen  have  the  peculiar  quality  described, 
and  why  is  it  so  different  from  the  pollen  of  other  nectar- 
bearing  flowers  ?  Answer  :  In  other  nectariferous  flowers 
the  pollen  is  to  be  rubbed  off  by  insects,  and  so  it  clings 
somewhat  firmly  in  order  that  the  wind  may  not  blow  it 
away.  In  this  flower,  however,  it  is  to  collect  in  the  lower 
part  of  the  funnel  in  order  to  be  able  to  fall  out  when  a  bee 
makes  an  opening.  So  if  it  remained  in  the  anthers,  the 
flower  would  never  be  fertilized.  Why  is  the  base  of  the 
style  so  slender  ?  Answer :  In  order  that  the  bee  may  lift 
up  the  style  the  more  easily.  But  why  is  this  base  a  little 
crooked  ?  and  why  does  the  retroflexed  end  of  the  style 
make  a  somewhat  acute  instead  of  a  right  angle  with  the 
style  ?  Answer :  Both  serve  the  same  purpose  as  the  last- 


246  Introduction  to  Botany. 

mentioned  condition.  The  direction  of  the  thrust  which 
the  bee  makes  against  the  retroflexed  end  of  the  style  is 
about  parallel  with  its  longer  straight  part.  This  thrust  is 
intended  to  lift  up  the  style  in  a  direction  about  at  a  right 
angle  with  its  long  axis.  Now  one  who  has  a  conception 
of  mechanics  will  see  that  this  would  not  occur  so  easily  if 
the  slender  base  of  the  style  were  straight  and  its  retro- 
flexed  end  made  a  right  angle  with  it.  The  retroflexed  end 
of  the  style  makes  an  oblique  angle  with  its  long  axis,  and 
consequently  with  the  direction  of  the  thrust,  for  the  very 
same  reason  that  the  surface  of  the  wings  of  a  windmill 
makes  an  oblique  angle  with  the  direction  of  the  wind.  And 
to  take  a  still  more  pertinent  example,  which  also  relates 
to  the  crooked  base  of  the  style,  let  one  imagine,  since  the 
style  has  a  similarity  to  a  crutch,  that  one  were  to  have  a 
crutch. made  exactly  after  the  pattern  of  it.  At  the  very 
first  trial  of  it  he  would  rue  his  idea,  for  should  he  put  his 
weight  upon  it  the  crutch  would  slip  out  and  he  would  fall. 
Finally,  why  does  the  membranous  appendage  of  the  upper 
filament  lie  in  part  upon  the  appendages  of  the  two  middle 
ones,  and  why  not  the  latter  or  one  of  them  upon  the 
former  ?  Answer  :  In  order  that  it  may  the  more  easily 
be  pushed  up  by  the  bee  through  the  agency  of  the  style. 
"  Now  I  will  relate  how  I  discovered  the  method  of  polli- 
nation of  this  flower.  An  observation  and  an  experiment 
helped  me  to  it  in  the  spring  of  last  year.  I  saw  that  the 
flowers  were  visited  by  bees,  and  I  wanted  to  imitate  the 
effect  which  they  make  upon  the  style ;  for  I  had  for  a 
long  time  conceived  that  the  whole  secret  must  lie  behind 
the  form  of  the  style  in  virtue  of  which  it  can  so  easily  be 
bent  upward  and  afterward  falls  back  again.  After  many 
fruitless  efforts  it  finally  happily  occurred  to  me  to  give 
the  plucked  flower  in  this  experiment  precisely  the  same 


Studies  of  Selected  Spermatophytes.         247 

position  which  nature  has  given  it.  That  was  beginning 
at  the  right  end  of  the  question,  for  as  soon  as  I  lifted  the 
flower  so  high  that  it  stood  above  the  level  of  my  eyes,  in 
order  to  be  able  to  look  into  it  from  below,  the  pollen  fell 
in  large  amount  out  of  the  funnel,  like  writing  sand  from 
the  sand-box,  as  soon  as  I  lifted  the  style  with  a  slender 
stick.  This  phenomenon,  which  actually  startled  me, 
because  I  had  not  expected  it,  was  to  my  understanding 
what  a  -flash  of  lightning  on  a  dark  night  is  to  the  eyes,  — 
it  revealed  on  a  sudden  the  whole  secret  to  me." 

Oenothera  speciosa  (or  other  species). 

What  is  the  habitat  of  this  plant  ?  Describe  the  leaves. 
What  sort  of  an  inflorescence  has  it  ?  Observe  the  arrange- 
ment of  the  floral  parts  in  the  bud.  At  what  time  of  day 
do  the  flowers  open  ?  How  long  does  a  flower  last  ? 
Describe  the  calyx  of  an  open  flower.  Do  the  anthers 
dehisce  before  or  after  the  flower  opens  ?  Are  the  stigmas 
ready  to  receive  the  pollen  as  soon  as  the  flower  opens  ? 
Draw  the  upper  part  of  the  style  before  and  after  the 
branches  spread  apart.  Note  the  position  of  the  style 
branches  when  the  flower  first  opens.  What  are  the 
relative  positions  of  anthers  and  stigmas  ?  Could  self 
pollination  take  place  if  cross  pollination  does  not  ?  What 
significance  do  you  attach  to  the  cobwebby  pollen  ?  Do 
the  flowers  become  more  fragrant  in  the  evening  ?  Where 
is  the  nectar  secreted  ?  How  long  must  an  insect's  pro- 
boscis be  to  get  it  ?  At  what  time  of  day  do  insects  visit 
these  flowers  ?  With  their  present  habits,  would  it  be  as 
well  for  these  flowers  to  be  any  other  color  than  white  ? 
Make  a  longitudinal  diagram  of  a  flower  and  a  cross  dia- 
gram of  an  ovary.  Compare  with  the  types  of  flowers  of 
Fig.  123.  To  what  type  does  this  flower  belong?  What 


248  Introduction  to  Botany. 

significance  do  you  see  in  the  different  positions  of  the 
flower  in  bud,  after  opening,  and  after  pollination  ?  Sum 
up  those  facts  which  relate  to  pollination. 

Asclepias  cornuti  (or  other  species). 

Read  the  account  of  Asclepias  cornuti  on  page  191. 
What  is  the  nature  of  the  underground  parts  ?  Describe 
the  leaves  and  inflorescence.  Break  off  a  leaf  or  stem 
and  note  the  exudation  of  latex.  Notice  later  how  the 
dried  latex  protects  the  wound.  Examine  the  exterior  of 
a  flower.  Can  the  pistils  be  seen  ?  Find  the  entrance  to 
the  stigmatic  chamber  (see  Fig.  108).  Slip  the  point  of 
a  needle  into  a  stigmatic  chamber  and  pass  it  upward 
and  out  at  the  top,  so  as  to  remove  the  corpusculum  and 
attached  pollinia  (see  Fig.  113).  Notice  the  slit-like 
opening  into  the' anther  cavities  through  which  the  pollinia 
are  extracted.  Draw  the  pollinia  as  seen  under  a  lens. 
Study  cross  sections  of  a  flower  at  different  heights,  and 
construct  a  diagram  showing  the  main  facts  learned.  In 
cutting  the  cross  sections  pollinia  will  frequently  be  seen 
lying  in  the  stigmatic  chambers  where  they  have  been 
deposited  by  insects,  and  in  the  older  flowers  pollen  tubes 
may  be  seen  penetrating  the  apex  of  a  style.  Study  the 
construction  of  the  spur-like  nectar  receptacles  growing 
from  the  stamens.  Observe  the  behavior  of  insects  at 
work  on  the  flowers.  Catch  a  bee  with  pollinia  adhering 
to  it  and  study  with  a  lens  the  way  in  which  the  pollinia  are 
made  fast  to  the  insect.  Point  out  the  deviations  from  the 
simpler  types  which  the  parts  of  this  flower  have  undergone, 
and  show  the  purposes  which  these  modifications  serve. 

Taraxacum  officinale. 

Is  this  plant  annual,  biennial,  or  perennial?  What  is  the 
nature  of  its  underground  parts?  What  descriptive  terms 


Studies  of  Selected  Spermatophytes.          249 

would  you  apply  to  its  leaves  ?  Make  a  longitudinal  section 
through  the  center  of  an  inflorescence  which  has  been  only 
a  short  time  in  bloom,  and  notice  the  unopened  buds  at 
the  center  and  the  fully  expanded  flowers  at  the  margin. 
The  disk  from  which  the  flowers  grow  is  the  receptacle  of 
the  inflorescence  (not  a  flower  receptacle).  Examine 
under  a  lens  the  apex  of  an  unopened  flower  and  note  the 
number  of  notches  in  the  corolla  indicating  the  number 
of  petals.  What  changes  does  the  corolla  undergo  as  it 
expands  into  the  open  flower?  Remove  an  entire  un- 
opened flower  from  the  receptacle  of  the  inflorescence, 
taking  care  not  to  break  off  the  ovary,  lay  it  on  the  stage 
of  the  microscope,  and  carefully  dissect  it  with  needles 
while  looking  at  it  through  the  lens.  How  many  stamens 
do  you  find  ?  Where  are  the  filaments  attached  ?  How 
many  style  branches  are  there?  What  relation  do  they 
bear  to  the  anthers  ?  Do  the  anthers  dehisce  toward  the 
inside  or  outside  ?  Notice  the  relative  heights  of  stamens 
and  styles  in  successively  older  flowers.  Note  the  behavior 
of  the  style  branches  up  to  the  time  of  the  withering  of 
the  flower.  How  is  the  pollen  pushed  out  from  the  tube 
formed  by  the  united  anthers  ?  The  stigmatic  surfaces 
being  along  the  inner  or  opposing  faces  of  the  style 
branches,  is  it  possible  for  self  pollination  to  take  place 
at  any  time  ?  The  nectary  occurs  near  the  base  of  the 
style,  and  the  nectar  is  expelled  into  the  tubular  part  of 
the  corolla.  See  whether  the  corolla  tube  ever  becomes 
filled  with  the  nectar.  Can  insects  probe  between  the  fila- 
ments to  reach  the  nectar  ?  Observe  the  behavior  of  bees 
on  these  flowers.  To  what  parts  of  their  bodies  does  the 
pollen  adhere  ?  Now  state  in  precise  terms  all  of  those 
facts  which  have  a  bearing  on  the  cross  or  self  pollination 
of  this  plant.  When  an  inflorescence  has  once  expanded, 


250  Introduction  to   Botany. 

does  it  ever  close  again  ?  Tie  a  string  loosely  around  a 
peduncle  to  mark  it,  and  observe  the  behavior  of  the  inflo- 
rescence on  cloudy  and  bright  days,  and  at  different  times 
of  the  day,  beginning  at  early  morning.  Try  to  conceive 
the  significance  of  what  you  find. 

Follow  the  changes  occurring  in  the  parts  of  the  flower 
up  to  the  time  of  the  scattering  of  the  fruit.  Make  draw- 
ings to  show  the  main  facts,  and  in  connection  with  them 
tell  what  these  facts  signify. 

Erigeron.     (Any  obtainable  species.) 

Study  the  inflorescence  and  flowers  as  directed  under 
Taraxacum,  and  compare  the  two  genera  by  means  of 
drawings  and  notes. 


CHAPTER  XL 

SLIME  MOULDS,   BACTERIA,  AND  YEASTS. 
PROVIDING   MATERIALS. 

The  materials  needed  for  the  work  of  this  chapter  can  be  obtained 
at  any  time  of  the  year,  as  directed  under  the  observations.  It  is  a  good 
plan,  however,  to  gather  the  sporangia  of  slime  moulds  whenever  they 
are  found  in  their  prime,  and  preserve  them  as  directed  on  page  370. 

OBSERVATIONS. 

Slime  Moulds. 

142.  Hunt  beneath  the  bark  of  rotting  logs  or  amongst 
the  moist  leaf  mould  of  woods  for  yellowish  or  gray  slimy 
growths  ;  the  plasmodia  of  slime  moulds.    Cut  off  a  portion 
of  the  log  bearing  the  plasmodium,  expose  to  the  light  and 
make  note  of  the  result.     Allow  another  portion  of  the  log 
bearing  the  plasmodium  to  dry  in  the  dark,  and  note  the 
result. 

143.  Place  some  of   the  plasmodium    under  a  bell  jar 
between    pieces   of   moist   felt   paper   (carpet   paper  will 
answer)  and  keep  the  preparation  in  the  dark,  and  moist 
but  not  wet.     The  plasmodium  will  probably  grow  out  over 
the  paper,  and  its  translocation  should  be  observed  from 
time  to  time.     Make  moist  chamber  preparations  of  the 
plasmodium  as  directed  under  Observation  108,  page  103. 
Watch  the  circulation  of  the  protoplasm  with  a  medium 
power  of  the  compound  microscope,  and  make  drawings  in 
which  the  direction  of  movement  is  indicated  by  arrows. 

251 


252 


Introduction  to  Botany. 


144.  The  preparation  under  the  bell  jar  will  finally  enter 
into  a  resting  condition,  and  sporangia  containing  spores 
may  be  produced.  Examine  the  sporangia  in  a  drop  of 
water  with  a  high  power  of  the  microscope,  and  draw  the 
spores.  Draw  the  sporangia  as  seen  under  low  power. 

DISCUSSION. 

150.  The  Nature  of  Slime  Moulds.  —  The  slime  moulds,  or 
Myxomycetes,  are  very  low  organisms  which  stand  at  the 


FIG.  132. 


Myxomycete  or  Slime  Mould,  i,  a  bit  of  plasmodium.  2,  a  small  plasmodium. 
3,  a  spore.  4  and  5,  protoplast  escaping  from  the  spore.  6  and  7,  stages  suc- 
ceeding 5,  motile  protoplasts  which  finally  fuse  to  form  2  and  i.  8  and  9,  dif- 
ferent forms  of  sporangia  bearing  spores  such  as  3.  After  PRANTL  and  MASSEY. 

boundary  line  between  the  lowest  plants  and  animals,  but 
the  character  and  nature  of  formation  of  their  spores  seem 
to  warrant  their  classification  among  plants.  In  its  vegeta- 
tive or  plasmodium  state  (see  Fig.  132)  a  slime  mould  creeps 


Slime  Moulds,  Bacteria,  and  Yeasts.         253 

about  in  moist  and  dark  places,  avoiding  the  light  and  being 
attracted  by  moisture ;  but  when  it  is  ready  to  form  its 
spores,  it  creeps  away  from  its  former  habitat  and  seeks  the 
light  at  the  surface  of  the  log  or  of  whatever  substratum  it 
is  inhabiting.  While  in  the  plasmodium  stage,  it  sends  out 
arms  here  and  there  that  may  surround  and  engulf  bits  of 
organic  matter,  which  it  digests  and  employs  as  food.  It 
does  not  possess  chlorophyll,  and  is  not,  like  green  plants, 
able  to  manufacture  its  own  food ;  for  this  reason  it  is 
restricted  in  its  habitat  to  the  remains  of  higher  plants 
which  yield  the  organized  materials  necessary  to  it. 

151.  Formation  of  Spores.  —  When  ready  to  produce 
spores,  the  plasmodium  puts  forth  outgrowths  which  be- 
come sporangia,  the  forms  of  which  vary  with  the  species 
(see  Fig.  132,  8  and  9).  At  the  surface  of  the  sporangia  a 
crust,  and  sometimes  a  variously  reticulated  framework,  is 
formed,  while  the  interior  protoplasm  breaks  up  into 
numerous  spores.  Sometimes,  among  the  spores,  threads 
are  formed  which  twist  and  untwist  with  the  changing 
humidities  of  the  atmosphere,  and  thus  aid  in  loosening  the 
spores  preparatory  to  their  dissemination  by  the  wind. 

When  a  spore  falls  into  a  wet  place,  its  protoplast,  which 
is  the  essential  part  of  it,  creeps  out  from  its  wall,  and 
(Fig.  132,  7)  being  provided  with  a  cilium,  swims  about 
in  the  water.  After  a  time  the  cilium  becomes  absorbed, 
and  the  protoplast  creeps  about  and  obtains  particles  of 
food  by  surrounding  them  bodily  (6).  While  in  this  con- 
dition it  may  multiply  by  repeated  division.  Finally,  many 
protoplasts  may  fuse  together  and  form  a  larger  multinucle- 
ated  body  similar  to  the  slimy  plasmodium  with  which  this 
description  began  (see  Fig.  132). 

It  often  happens  that  when  the  substratum  is  drying  up 
the  plasmodium  changes  into  dry  masses  of  various  shapes, 


254  Introduction  to  Botany. 

which  again  form  plasmodia  under  proper  conditions  of 
humidity,  etc.  Such  dry  masses  may  be  incited  to  resume 
their  active  creeping  stage  by  being  kept  between  moist 
felt  paper  under  a  bell  jar. 

OBSERVATIONS. 

Bacteria  and  Yeasts. 

145.  Put  hay,  cabbage   leaves,  or  beans  to  soak  in  a 
beaker  of  water,  and  leave  the  infusion  standing  in  a  warm 
place  until  the  liquid  becomes  cloudy.     Then  examine  a 
drop  under  a  high  power ;  minute  bodies  of  various  forms 
will  be  seen,  some  of  them  in  rapid  motion.     The  smaller 
rounded,  rod-shaped,  or  corkscrew-shaped  bodies  are  bac- 
teria, the  smallest  known  plants. 

146.  Boil  a  potato  and  cut  it  in  two  with  a  knife  which 
has  been  sterilized  by  baking  in  an  oven.     Dip  into  the 
above  infusion  the  point  of  a  needle  which  has  been  steril- 
ized in  the  flame  of  an  alcohol  lamp  or  Bunsen  burner, 
and  then  lightly  make  a  few  scratches  with  the  point  of 
the  needle  across  the  full  length  of  the  cut  surface  of  the 
potato.     Put  the  inoculated  potato  under  a  bell  jar  or  other 
dish,  together  with  some  moistened  filter  paper  to  keep  the 
potato  from  becoming  dry.     Examine  the  preparation  from 
day  to   day.     Mount    under   a   coverglass    some    of   the 
growths  which  appear,  and  examine  with  a  high  power. 
Doubtless  growths  will  appear  on  the  potato  outside  the 
scratches,  because   not   enough   care   has   been  taken  to 
exclude  the  possibility  of  accidental  inoculation  ;    but  the 
growths  along  the  scratches  will  be  sufficiently  definite  for 
our  present  purpose. 

The  experiment  might  be  varied  by  touching  one  half  of 
the   potato   against   some   dusty  place   in  the  room,  and 


Slime   Moulds,   Bacteria,  and  Yeasts.         255 

placing  the  other  half  beside  it  under  the  bell  jar.  Record 
your  observations  in  your  notes.  Thread-like  growths  may 
appear  among  the  spots  of  bacterial  colonies;  these  are 
Fungi,  which  are  higher  in  the  scale  of  life  than  the  bacteria. 
They  should  be  left  to  form  their  spores  undisturbed  for 
use  in  a  subsequent  study. 

147.  Put  milk  into  a  clean  flask,  plug  tightly  with  a  wad 
of  cotton,  and  steam  in  a  steamer  for  half  an  hour  on  each 
of  three  successive  days.     The  milk  should  be  found  to 
continue  sweet  for  an  indefinite  period. 

148.  Remove  on  the  point  of  a  needle  a  very  small  por- 
tion of  bacterial  material  from  Observation  146  (or  take  a 
small  drop  of  the  culture  of  Observation  145)  and  place  it 
in  a  drop  of  water  at  the  center  of  a  glass  slip,  and  stir  the 
drop  with  a  needle  to  thoroughly  distribute  the  bacteria. 
Let  the  water  evaporate,  and  then  pass  the  slip,  prepara- 
tion side  up,  three  times  through  the  flame  of  an  alcohol 
lamp,  each    passage  through  the  flame  occupying  about 
one  second.     This  fixes  the  bacteria  to  the  slip.     Place  a 
drop  of  a   i  Jfc  aqueous  solution  of  fuchsin  on  the  prepara- 
tion, and  wash  it  off  after  a  minute  in  running  water,  or 
by  moving  it  about  in  a  dish  of  water.     Then  pass  the 
preparation    two    or    three   times   quickly   through   60 Jfe 
alcohol  to  decolorize  the  background.     Let  the  prepara- 
tion dry   and  mount  in  Canada  balsam  (see  page  390). 
Draw  the  different  forms  of  bacteria  clearly  brought  out 
by  the  stain. 

149.  Soak  a  piece  of  yeast  cake  over  night  in  a  saucer 
of  water,  and  then  mount  a  very  small  portion  of  it  in  a 
drop  of  water  under  a  coverglass.     Spread  the  yeast  out 
in  a  thin  layer  by  giving  the  coverglass  a  circular  motion 
by  means  of  the  point  of  the  finger,  covered  with  a  clean 
cloth  to  avoid  smirching  the  coverglass.     Examine  with  a 


156  Introduction  to  Botany. 

high  power.  A  various  assemblage  of  small  objects  will  be 
seen.  Run  a  drop  of  iodine  under  the  coverglass  ;  the  ob- 
jects colored  blue  or  almost  black  by  this  reagent  are  starch 
grains,  which  make  up  the  bulk  of  a  cake  of  yeast,  while 
the  round  or  oval  yellowish  bodies  are  yeast  plants.  The 
still  smaller  rods  and  rounded  bodies  are  bacteria.  Some  of 
the  yeast  plants  will  be  found  in  the  process  of  reproduc- 
tion by  budding  (Fig.  133,  a).  Yeast  plants  are  efficient 
in  making  bread  light,  as  will  be  shown  in  the  discussion. 

150.  Mix  about  two  teaspoonfuls  of  molasses  with  a 
pint  of  water  and  add  a  small  piece  of  yeast  cake.  Fill  a 
wide-mouth  bottle  with  the  mixture  and  invert  it  in  a  dish 
of  the  same.  To  keep  the  liquid  from  running  out  of  the 
bottle  while  inverting  it,  fill  the  bottle  quite  full  and  place 
a  piece  of  stiff  paper  over  the  mouth  and  hold  the  paper 
in  position  with  the  tips  of  the  fingers  while  inverting  the 
bottle  and  placing  it  in  the  dish ;  then  remove  the  paper. 
Keep  the  preparation  in  a  warm  place.  After  a  time 
bubbles  of  gas  will  arise  and  displace  the  liquid.  When 
a  sufficient  quantity  of  gas  has  been  secured,  it  can  be 
demonstrated  to  be  carbon  dioxide  by  the  methods  de- 
tailed on  page  13.  The  solution  will  now  be  found  to 
have  an  alcoholic  taste,  and,  if  it  is  properly  distilled, 
alcohol  can  be  obtained  strong  enough  to  burn. 

DISCUSSION. 

152.  Nature  of  Bacteria.  —  The  bacteria  are  the  smallest 
of  known  plants,  the  rounded  forms  being  about  .0001  mm. 
in  diameter;  the  oblong  and  rod-shaped  forms  are  no  greater 
than  this  in  their  short  diameter,  as  a  rule,  and  their  long 
diameter  is  from  ij  to  5  times  as  great.  They  are  there- 
fore still  very  small  in  appearance,  even  when  magnified 
with  the  highest  powers  of  the  microscope,  and  it  is-  difficult 


Slime   Moulds,   Bacteria,  and  Yeasts.         257 

to  determine  the  details  of  their  construction.  They  are 
enveloped  by  an  extremely  thin  translucent  membrane. 
Whether  they  have  nuclei  is  a  question  which  is  still  in 

t¥  1%  ti 


',    v   tv-     I 


'•-•»•/ 

t     l> 


*    V       V 


c  FIG.  133.  d 

a,  yeast  plants,  some  of  them  budding;  b,  micrococci  (singular,  micrococcus)  from 
the  air;  c,  Bacillus  subtilis,  showing  internal  spore-formation;  d,  bacilli  (singu- 
lar, bacillus)  of  Asiatic  cholera,  with  motile  flagella.  Photomicrographs  X  740. 
After  GUNTHER. 

doubt.     It  is  thought  by  some  that  the  bulk  of  their  bodies 
is  made  up  of  nuclear  material. 

153.  Methods  of  Reproduction.  —  Bacteria  reproduce  by 
division,  one  becoming  two,  two  four,  and  so  on.  Asexual 
spores  are  also  formed,  either  by  the  ordinary  cells  pro- 


258  Introduction  to  Botany. 

duced  by  division  assuming  a  spore  character,  or  by  the 
cell  contents  rounding  off,  expelling  water,  and  entering 
into  a  condition  in  which  great  extremes  of  heat,  cold,  and 
desiccation  can  be  withstood  (see  Fig.  133,  c).  While  in 
the  vegetative  state,  most  bacteria  are  killed  at  a  tempera- 
ture of  65°  C,  their  spores  can  stand  100°,  or  in  some 
cases  130°  C.,  of  dry  heat;  but  no  spores  can  withstand  an 
air-free  steam  heat  of  120°  C.  for  half  an  hour.  This  high 
temperature  is  achieved  by  generating  the  steam  under 
ij  atmospheres'  pressure  in  an  apparatus  known  as  an 
autoclave. 

The  spores  are  very  resistant  to  cold ;  freezing  does 
not  affect  them,  and  they  have  been  known  to  survive 
even  after  exposure  for  a  short  time  to  the  temperature 
of  freezing  oxygen,  namely,  213°  C.  below  zero.  By  a 
process  known  as  discontinuous  heating  they  may  be 
killed  at  100°  C.  By  this  method  the  heating  is  carried 
on  for  half  an  hour  on  each  of  three  consecutive  days. 
The  explanation  of  the  success  of  this  process  is  that  most 
of  the  spores  which  resist  the  first  heating  will  probably 
have  germinated,  and  so  have  passed  into  a  less  resistant 
state,  by  the  time  of  the  second  heating.  The  third  heat- 
ing is  certain  to  destroy  the  remaining  bacteria,  since  all  of 
the  spores  will  have  germinated  by  that  time. 

154.  Forms  of  Bacteria.  —  In  form,  bacteria  are  round, 
oblong,  rod-shaped,  or  spiral  (Figs.  133-134).     But  while 
exceedingly  simple  in  the  construction  and  contour  of  their 
bodies,  the  results  of  their  activities  are  quite  diverse,  and 
of  vast  importance  to  other  plants  and  animals. 

155.  Nutrition  of  Bacteria.  —  Although  bacteria  may  pro- 
duce pigments  of  various  colors,  they  do  not  form  chloro- 
phyll  and    cannot   obtain  their  living  by  employing  the 
energy  of  'the  sunlight  to  build  their  food ;    they   must, 


Slime  Moulds,   Bacteria,  and  Yeasts.         259 

therefore,  live  upon  materials  already  organized,  or  they 
must  utilize  some  source  of  energy  other  than  the  sunlight 
for  the  construction  of  their  food.  Most  bacteria  have 
adopted  the  former  course,  and  obtain  their  sustenance  from 


FIG.  134. 


e,  bacilli  of  typhoid  fever ;  f,  bacilli  of  chicken  cholera ;  g,  bacilli  of  splenic  fever ; 
h,  spirillum  of  recurrent  fever,  and  red  blood  corpuscles.  Photomicrographs 
X  740.  After  GUNTHER. 

the  bodies  or  products  of  plants  and  animals.  Others, 
however,  are  able  to  induce  the  oxidation  of  compounds  of 
nitrogen,  sulphur,  iron,  etc.,  and  appropriate  the  heat  thus 
produced  for  the  fixation  of  carbon  from  carbon  dioxide, 
much  as  green  plants  do  by  means  of  the  sunlight.  To 


160  Introduction  to  Botany. 

show  the  importance  of  bacteria  in  the  economy  of  nature, 
a  brief  statement  will  be  made  of  some  of  the  things  which 
are  known  to  be  accomplished  by  them. 

156.  Bacteria  of  Economic  Importance.  —  There  are  forms 
existing  in  the  soil,  known  as  nitrifying  bacteria,  which 
bring  about  the  oxidation  of  certain  nitrogen  compounds 
brought  down  by  rains  or  resulting  from  the  decay  of  plant 
and  animal  bodies,  nitric  acid  being  produced,  —  a  sub- 
stance absolutely  necessary  to  the  nutrition  of  plants.     Its 
production  by  the  bacteria  is  of  great  importance,  since  it 
exists  in  the  soil  in  relatively  minute  quantities  and  is  easily 
carried  away  by  percolating  water. 

Bacteria  of  another  kind  inhabit  the  root  tubercles  of 
leguminous  plants,  and,  taking  the  free  nitrogen  of  the  air, 
build  it  into  the  constitution  of  their  own  bodies.  Finally 
the  bacteria  appear  to  be  digested  and  appropriated  as 
food  by  the  leguminous  plants  (Fig.  13).  In  this  way  the 
green  plant  is  able  to  obtain  indirectly  the  free  nitrogen  of 
the  atmosphere,  which  otherwise  would  be  inaccessible  to 
it.  A  knowledge  of  these  facts  is  of  utility  to  agriculture, 
for  land  naturally  poor  in  nitrogen  can  be  sown  to  alfalfa 
or  plants  of  similar  character,  which,  when  plowed  under, 
leave  the  land  much  richer  in  nitrogen  than  it  was  before. 
It  has  been  found  practicable  to  inoculate  with  liquid  cultures 
of  the  bacteria  soils  which  do  not  naturally  contain  them. 
The  importance  of  these  bacteria  to  leguminous  plants  grow- 
ing in  soils  poor  in  compounds  of  nitrogen  is  shown  by  the 
experiment  illustrated  in  Fig.  135. 

Other  forms  are  instrumental  in  the  production  of  vinegar 
from  alcohol,  in  the  proper  ripening  of  cheese,  and  others 
add  to  the  agreeable  flavor  of  butter,  as  has  been  efficiently 
demonstrated  in  the  dairies  of  Finland  and  Denmark. 

157.  Disease-producing  Bacteria.  —  There  are  other  forms 


Slime   Moulds,  Bacteria,  and  Yeasts.         261 


which  are  injurious  instead  of  beneficial,  such  as  those  pro- 
ducing consumption,  diphtheria,  typhoid  fever,  lockjaw, 
blood  poisoning,  bubonic  plague,  etc.  (Figs.  133-134). 
These  diseases  are  brought  about 
by  poisons  produced  by  the  bac- 
teria within  the  body.  Great 
advances  in  surgery  and  in  the 
treatment  and  prevention  of  dis- 
eases have  been  made  by  an  un- 
derstanding of  the  life  history 
and  habits  of  these  microscopic 
forms  of  life.  It  is  now  known, 
for  instance,  that  gangrene  and 
blood  poisoning,  which  formerly 
often  followed  in  the  wake  of 
surgical  operations,  were  brought 
about  by  bacteria  clinging  to  the 
surgeon's  knife,  or  which  were 
in  the  water,  bandages,  etc.,  used 
in  dressing  the  wound.  Now 
every  instrument  or  object  em- 
ployed in  such  operations  is  thor- 
oughly sterilized,  and  the  healing 
of  the  wound  goes  forward  with- 
out complications.  So,  too,  it  is 

now  known  that  the  expectorations  of  consumptives  and 
the  dejecta  of  typhoid  patients  are  teeming  with  the  bac- 
teria causing  these  diseases,  and  that  unless  the  bacteria 
are  destroyed  by  suitable  poisons  or  heat  they  may  spread 
disease. 

158.  The  Nature  of  Yeasts.  —  Yeasts  are  low  forms  of 
plants  which,  like  bacteria,  are  destitute  of  chlorophyll, 
and  are  dependent  for  their  food  upon  materials  built  up 


FIG.  135. 

Experiment  showing  the  impor- 
tance of  nitrogen-fixing  bacteria 
to  leguminous  plants,  t,  peas 
grown  in  a  nitrogen-free  soil  with 
bacteria;  u,  the  same  in  all  re- 
spects, but  without  bacteria.  Af- 
ter FRANK. 


262  Introduction  to  Botany. 

by  green  plants.  They  are  rounded  or  ellipsoidal  (Fig. 
133>  a\  and  are  about  .0015  to  .015  millimeter  in  diameter. 
Each  individual  consists  of  a  single  protoplast,  surrounded 
by  a  delicate  wall.  Investigation  into  the  life  history  of 
yeasts  seems  to  have  shown  that  they  are  really  spore-like 
forms  which  have  been  produced  by  certain  species  of 
filamentous  Fungi,  but  however  this  may  be,  the  yeasts 
are  capable  of  sustaining  an  independent  existence,  and 
of  multiplying  both  by  budding  and  by  internal  spores. 

159.  Reproduction  of  Yeasts.  —  In  budding,  a  knob-like 
outgrowth  is  produced  which  finally  becomes  separated  and 
grows  to  the  size  of  the  individual  from  which  it  sprang. 
In  internal  spore-formation,  the  cell  protoplasm  breaks  up 
into  several  rounded  bodies  that  escape  and  finally  germi- 
nate, producing  forms  like  the  one  from  which  they  sprang. 
The  internal  spores  are  apt  to  be  formed  when  the  food  is 
running  short ;  and  they  are  evidently  useful  in  tiding  over 
unfavorable  conditions. 

160.  Yeasts  in  Bread-making.  —  Yeasts  obtain  part  of 
their  food  from  weak  solutions  of  sugar,  and  in  so  doing 
convert  the  sugar  into  alcohol  and  carbonic  acid ;    their 
usefulness  in  the  raising  of  bread  is  due  to  this  action. 
When  the  sponge  is  made,  the  ferment  known  as  diastase, 
which  was  produced  in  the  grain  of  wheat  for  the  purpose 
of  digesting  the  starch  when  the  seed  germinates,  carries 
on  the  process  of  starch  digestion  in  the  sponge,  changing 
a  part  of  the  starch  into  grape  sugar.     Then  the  yeast 
plants  begin  their  action  on  the  sugar,  and  the  carbon  di- 
oxide produced  along  with  the  alcohol  becomes  entangled 
in  the  sticky  mass  and  causes  it  to  puff  up.     If,  now,  while 
the  gas  is  still  forming,  the  flour  is  worked  in  with  the 
sponge,  the  gas  is  produced  at  all  points  throughout  the 
mass  of  dough  and  raises  it.     The  alcohol  which  is  produced 


Slime  Moulds,  Bacteria,  and  Yeasts.         263 

at  the  same  time  is  driven  off  in  the  process  of  baking.  If 
the  bread  is  allowed  to  stand  too  long  before  baking,  the 
alcohol  is  attacked  by  bacteria  which  change  it  into  acids, 
and  the  dough  is  soured. 

161.  Yeasts  in  Alcoholic  Fermentation.  —  There  are  vari- 
ous sorts  of  yeasts  which  produce  alcohol,  and  some  other 
little-known  substances  that  give  flavor,  bouquet,  etc.,  in  the 
manufacture  of  beer,  wine,  and  other  fermented  liquors. 
In  recent  years  these  various  kinds  of  yeasts  have  been 
grown  separately,  and  are  used  in  the  production  of  distinct 
kinds  of  beer  and  wine.  Some  yeasts  seem  also  to  be  the 
cause  of  disease  in  man  and  the  lower  animals. 


CHAPTER   XII. 
ALGJE,  FUNGI,  AND  LICHENS. 

PROVIDING  MATERIALS. 

Algae  and  Fungi  should  be  gathered  in  both  vegetative  and  fruiting 
conditions  and  preserved  in  formalin.  Many  of , the  fresh- water  Algas 
do  well  in  glass  jars  of  water  kept  in  a  well-lighted  place  in  the  labora- 
tory. Spirogyra  and  Oedogonium  are  very  amenable  to  this  sort  of 
treatment.  Reproductive  stages  will  be  found  in  abundance  in  early 
spring  and  summer.  Vaucheria  can  usually  be  obtained  in  greenhouses, 
growing  on  flower  pots,  etc.,  at  any  season  of  the  year.  Out  of  doors 
it  should  be  sought  on  moist  and  shady  banks  near  the  water's  edge ; 
and  when  found  in  good  condition  to  show  the  method  of  sexual  repro- 
duction it  should  be  preserved  in  formalin.  One  may  secure  Pleurococcus 
at  any  time  of  the  year  on  the  shady  side  of  trees,  etc.,  bread  mould  and 
Fungi,  of  a  similar  character  as  directed  under  Observation  160,  and 
rusts,  smuts,  and  mildews  in  great  abundance  at  almost  any  time  during 
the  growing  season.  The  last  may  be  preserved  either  dry,  in  forma- 
lin, or  in  70%  alcohol.  Toadstools  and  their  kind  can  be  collected  in 
pastures  and  open  woods  at  any  time  during  the  growing  season  when 
the  weather  is  not  too  dry.  Lichens  are  to  be  found  on  trees,  old 
fences,  and  on  rocks  at  any  time. 

OBSERVATIONS. 
ALG.E. 

151.  Cut,  from  the  north  side  of  a  tree,  bark  which  is 
covered  with  a  green  mealy  growth ;  moisten  with  water, 
and  place  on  wet  filter  paper  under  a  bell  jar  for  several 
hours.  Observe  the  character  of  the  growth,  first  with 
the  naked  eye  and  then  with  a  simple  lens.  Scrape  up 

264 


Algae,  Fungi,  and  Lichens.  265 

some  of  it  with  the  point  of  a  knife,  and  notice  whether 
it  readily  breaks  up  into  small  particles.  Observe  the  tree 
on  which  it  was  growing.  Is  the  growth  always  on  the 
north  side  ?  How  far  up  the  trunk  does  it  extend  ? 

152.  Scrape  up  a  small  portion  of  the  growth  with  the 
point  of  a  knife,  taking  care  not  to  remove  the  bark,  and 
mount  under  a  coverglass  in  a  drop   of  water.     Place  a 
clean  cloth  over  the  forefinger  and  move"  the  coverglass 
about  gently,  in  order  to  spread  out  the  preparation  in  a 
thin  film.     If  the  pressure  of  the  finger  is  too  great,  the 
little  plants  will  be  broken.     Examine  with  a  high  power, 
and  pick  out  what  appears  to  be  a  single  individual.    How 
do  you  account  for  the  clusters  of  individuals  which  are 
found  ?     Does  the  green  color  occur  in  definite  chloro- 
plasts  ?    Treat  the  preparation  with  chloral  hydrate-iodine. 
Does  starch  appear  ?    Is  there  any  difference  in  this  respect 
between  material  which  has  been  kept  in  the  dark  and  that 
which  has  been  exposed  to  the  bright  light  of  the  northern 
sky,  but  not  to  the  direct  rays  of  the  sun  ?     Can  you  tell 
why  some  trees  seem  to  possess  this  growth  more  than 
others  ? 

153.  Examine   some  of   the   green   filamentous   plants 
which  occur  in   ponds,  lakes,  or  small  running  streams. 
Do  they  float  freely  in  the  water  or  are  they  fastened 
down  in  any  way  ?     How  do  you  account  for  the  bubbles 
of  gas  which  collect  about  these  plants  in  the  sunlight? 
Is  there   any  difference  in  this   respect   between   plants 
which  are  freely  exposed  to  the  sun  and  those  which  are 
deeply  shaded  ?     If  so,  what  is  the   significance  of  the 
difference  ? 

154.  Pick  up  some  of  the  material  and  spread  it  out  in 
the  hand.     Can  you  distinguish  the  individuals  of  which  it 
is  composed  ?     Can  you  distinguish  the  parts  of  which  the 


266  Introduction  to  Botany. 

individuals  are  composed  ?     Leave  some  of  the  plants  out 
of  the  water  for  a  time,  and  note  what  occurs  to  them. 

155.  Spread  out  a  few  of  the  individuals  in  a  drop  of 
water   under  a  coverglass   and  examine  with  a  medium 
power  of   the  microscope.      Do   the   parts  of   which   the 
individuals  are  composed  differ  from  each  other  in  any 
essential  way  ?    Note  the  character  of  the  walls  and  of  the 
contents.     Is  a  nucleus  to  be  seen  ?     What  is  the  form 
of   the  chloroplasts  ?  .  Treat  a   preparation  with   chloral 
hydrate-iodine,  and  note  whether  starch  is  demonstrated. 
Does  the  nucleus  become  more  prominent  for  a  time  while 
the  protoplasm  is  dissolving  ? 

156.  Examine   some   of    the   green,   filamentous,  felty 
growth  which  abounds  on  moist  shady  banks.     Is  it  ever 
found  in  sunny   situations  ?     Examine  some  of   the  fila- 
ments, and  try  to  determine  how  they  are  held  together  to 
form  the  felty  mass.     Are  they  anchored  to  the  earth,  or 
do  they  simply  grow  over  its  surface  ? 

157.  Mount  some  of   the  filaments  in  a  drop  of  water 
under  a  coverglass.      Are  they  composed  of  cells,  or  does 
each  filament  appear  to  be  one  large  cell?     Locate  the 
chloroplasts.     Can  more  than  one  nucleus  be  found  ? 

158.  If  living  near  the  seacoast,  observe  the  bladder- 
wrack.     How  is  it  fastened  to  its  substratum  ?     Is  there 
any  special  device  to'  keep  the  free  parts  buoyed  up  in  the 
water?     Examine  the  enlarged  ends  and  press  them  be- 
tween thumb  and  finger  while  observing  them  with  a  lens. 
Make  thin  sections  through  the  swollen  pitted  ends,  mount 
in  a  drop  of  water  under  a  coverglass,  and  examine  with  a 
medium  power.     Small  cavities,  or  conceptacles,  should  be 
seen  opening  exteriorly.     In  our  common  bladder-wrack, 
Fucus  vesictilosus,  these  cavities  will  be  found  to  contain 
either  the  eggs  or  the  sperms,  this  species  being  dioecious. 


Algae,  Fungi,  and  Lichens.  267 

159.  Make    sections  through  the  enlarged  bladder-like 
portions   of   the   plant.     Do   they  contain  air   or  water  ? 
What  is  their  evident  purpose?     Make  sections  through 
the  other  portions  of  the  plant,  and  examine  under  the 
microscope.     Although   the   plant   has  a  brown  color,  it 
really  contains  chlorophyll,  whose  character  is  masked  by 
the  brown  coloring  matter  associated  with  it  in  the  chloro- 
plasts.     By  what  means  is  this  plant  held  in  proper  condi- 
tion to  catch  the  sunlight  ? 

FUNGI. 

1 60.  Moisten  stale  bread  in  water  and  place  it  under  a 
bell  jar  in  a  warm  place.     To  be  more  certain  of  obtaining 
what  is  wanted,  place  under  the  bell  jar  some  lemon  pulp 
and  rind  from  which  the  juice  has  been  squeezed,  of  pieces 
of  partly  decayed  sweet  potato  or  banana.     Various  sorts 
of  growths  will  appear,  but  the  filamentous  growths  which 
in  a  few  days  bear  minute  spore  cases  on  thread-like  stems, 
are  the  forms  desired  for  this  study. 

161.  Determine  whether  the  filaments  making  up   the 
body  of  the  growth  penetrate  the  substratum  or  simply  lie 
on  its  surface.     Examine  with  a  lens  the  spore  cases,  or 
sporangia,  of  different  ages.     With  a  pair  of  forceps,  care- 
fully pull  off  sporangia  of  different  stages  of  development, 
and  mount  under  a  coverglass  in  a  drop  of  70^  alcohol. 
(Alcohol   is   used  instead   of   water   because  air  bubbles 
adhere  to  the  material  when  water  is  used,  but  after  mount- 
ing in  alcohol  a  drop  of  water  may  be  placed  on  the  slide 
in  contact  with  the  coverglass,  and  as  the  alcohol  evapo- 
rates the  water  will  take  its  place.)     Note  the  appearance 
of  the  spores  in  the  sporangia  of  different  ages.     Why  do 
the  old  sporangia  appear  black  ? 

162.  Soak  a  cubical  block  of  stale  bread  in  water,  sow 


268  Introduction  to  Botany. 

spores  from  the  old  sporangia  over  all  sides  of  it,  and  keep 
it  in  a  moist  atmosphere  under  a  bell  jar.  When  the 
sporangia  appear,  note  whether  they  all  stand  upright,  or 
whether  the  direction  taken  by  them  bears  a  definite 
relation  to  the  surface  of  the  bread.  Expose  them  to  the 
light  so  that  they  will  be  illuminated  on  one  side  more  than 
on  another,  and  note  whether  the  direction  taken  by  the 
stems  which  bear  the  sporangia  is  affected  in  any  way. 

163.  Examine  the  surface  of  a  rusted  leaf  of  wheat, 
oats,  or  any  of  the  wild  grasses.     Does  the  rust  appear 
on  the  veins  or  between  them  ?     Examine  with  a  lens  and 
note  whether  the  epidermis  of  the  leaf  has  been  broken  by 
the  rust.     Can  any  growths  not  belonging  to  the  leaf  be 
seen  ? 

164.  Make  thin  sections  of  the  leaf  across  the  rusted 
spots,  and  mount  under  a  coverglass  in  a  drop  of  water. 
If  the  leaf  is  dry,  soak  it  for  a  few  hours  in  water  before 
sectioning.     The  section  of  the  leaf  should  be  so  thin  that 
the  spores  of  the  rust  and  the  cells  of  the  leaf  immediately 
beneath  may  readily  be  seen.     The  parts  may  be  rendered 
more  transparent  by  mounting  the  section  in  a  saturated 
solution    of   chloral   hydrate.     Notice  the    course  of   the 
thread-like  part  of  the  rust  which  penetrates  the  interior  of 
the  leaf. 

165.  Does   the   rust    appear    to   produce    any    serious 
mechanical  injury  to  the  tissues  of  the  leaf  ?     In  what  ways 
is  the  injury  to  the  plant  probably  produced?     Does  the 
rust  appear  to  have  any  means  of  manufacturing  its  own 
food  independently  of  the  plant  on  which  it  is  growing  ? 
What  have  you  observed  in  regard  to  the  ravages  of  rust  in 
wheat  fields,  etc.  ? 

1 66.  Examine   a   toadstool   growing   in    the  woods    or 
pasture.     Dig   away  the  soil  carefully  at  its  base  to  see 


Algae,  Fungi,  and  Lichens.  269 

what  sort  of  connection  it  has  with  the  substratum.     Can 
smaller  toadstools  be  found  just  above  or  beneath  the  soil  ? 

167.  Break  off  the  cap  of  the  toadstool  and  lay  it  on  a 
piece  of  blue  paper  where  it  will  not  be  disturbed,  and  after 
a  day  or  so  remove  the  cap  and  note  what  has  happened. 

1 68.  Make  thin  sections  across  the  gills,  and  mount  in  a 
drop  of  70^)  alcohol,  and  with  a  high  power  look  for  the 
spores  growing  from  the  gills.     Examine  with  the  same 
power  some  of  the  deposit  found  on  the  paper  of  Observa- 
tion 167,  and  compare  with  the  spores  found  growing  to  the 
gills. 

169.  Examine  the  bark  of  old  trees  in  a  wood  for  the 
discolored  spots  and  scale-like  growths  known  as  Lichens. 
Is  the  body  of  the  Lichen  all  alike,  or  does  some  part  appear 
to  be  spore-bearing  ?     Cut  off  the  Lichen  from  the  bark  and 
soak  for  a  day  in  water,  then  make  thin  sections  through 
the  spore-bearing  part  and  mount  in  a  drop  of  water.     Of 
what  is  the  body  of  the  Lichen  found  to  consist  ?    Are  there 
any  parts  containing  chlorophyll  ?     Observe  the   slender 
sacs   in  which  the  spores   are  borne.     How  do   Lichens 
probably  obtain  the  water  necessary  to  their  growth  ?     Do 
they  make  a  slow  or  a  rapid  growth  ? 

DISCUSSION.  —  ALG^; 

162.  Nature  of  Algae.  —  The  Algae,  of  which  we  have 
seen  examples  in  the  green  growth  on  trees,  in  the  filamen- 
tous green  growths  in  water  and  on  shady  banks,  and  in 
the  bladder-wrack  of  the  ocean,  are  low  forms  of  plants  of 
very  simple  construction,  except  in  the  case  of  the  larger 
seaweeds.  They  consist  for  the  most  part  of  single  cells, 
or  of  rows  of  similar  cells  joined  end  to  end  to  form  fila- 
ments. They  contain  chlorophyll,  and  so  are  able  to  make 


2JO 


Introduction  to  Botany. 


use  of  the  carbon  dioxide  of  the  air,  or  of  the  water  in 
which  they  reside,  in  the  same  manner  as  do  the  more 
complex  green  plants.  Having  need  of  the  sunlight,  they 
usually  float  near  the  surface  if  their  habitat  is  water ;  but 
if  they  live  on  the  land,  they  are  adapted  only  to  moist  and 
shady  situations.  They  have  no  waterproof  protective 

covering  such  as  is  furnished 
by  the  cuticle  of  the  higher  land 
plants,  and  accordingly  quickly 
dry  up  if  exposed  to  a  dry  at- 
mosphere. 

163.  Pleurococcus  Viridis.  — 
Pleurococcus  viridis,  which  we 
found  as  a  mealy  green  growth 
on  the  north  side  of  trees,  is  one 
of  the  simplest  of  the  Algae.  As 
has  been  seen,  an  individual  con- 
sists of  a  single  globular  cell, 
having  an  outer  transparent  wall 
of  cellulose,  a  nucleus  which  is 
difficult  to  see,  and  a  few,  rela- 
tively large  chloroplasts  occupying  the  bulk  of  the  cell  (Fig. 
136).  This  single,  minute  individual  is  equipped  to  sustain 
an  independent  existence,  being  able  to  perform  within 
its  small  compass  the  necessary  nutritive  and  reproductive 
functions.  But  since  it  consists  of  a  single  cell,  it  is 
unable  to  construct  special  systems  for  the  separate  func- 
tions ;  and  it  is  therefore  restricted  to  habitats  which  by 
their  nature  protect  it  against  too  great  transpiration,  the 
beating  of  storms,  and  other  sources  of  mechanical  in- 
juries. The  thin  and  delicate  wall  necessary  to  allow  the 
ingress  of  its  raw  food  materials  will  not  permit  it  to  exist  in 
places  which  are  dry  or  fully  exposed  to  the  sun.  We  may 


FIG.  136. 

Pleurococcus  viridis.  a,  a  single 
individual ;  b,  c,  and  d,  various 
stages  in  cell  division.  The 
chloroplasts  are  so  crowded  that 
no  attempt  has  been  made  to 
distinguish  them  in  the  figure. 


Algae,  Fungi,  and  Lichens.  271 

look  upon  it  as  one  of  the  simplest  forms  which  have 
essayed  to  appropriate  the  energy  of  the  sunlight  for  the 
manufacture  of  their  food;  and  it,  or  some  form  not  dis- 
tantly related  to  it,  probably  represents  the  very  primitive 
organism  from  which  the  higher  plants  have  been  evolved. 

Pleurococcus  multiplies  by  cell  division,  one  becoming 
two,  two  four,  etc.,  as  in  the  case  of  the  bacteria.  When 
examined  under  the  microscope,  the  individuals  are  usually 
found  adhering  in  groups  in  a  manner  which  suggests  that 
they  are  on  the  border  land  of  unicellular  and  multicellular 
forms. 

164.  Spirogyra.  —  Among  the  forms  of  filamentous  Algae 
taken  from  fresh  water,  Spirogyra  and  Oedogonium  are 
quite  likely  to  occur.  The  method  of  reproduction  of 
Oedogonium  has  already  been  described  on  page  163,  and 
Spirogyra  (Fig.  137)  will  now  be  used  as  a  type  of  fila- 
mentous Algae.  Each  individual  consists  of  similar  cells 
joined  end  to  end.  The  cytoplasm  lines  the  cell  wall,  leav- 
ing a  large  vacuole  filled  with  cell  sap.  Embedded  in  the 
cytoplasm  are  one  or  more  elongated  and  spirally  coiled 
chloroplasts.  A  rather  large  nucleus  is  suspended  at  the 
center  of  the  cell  by  arms  of  cytoplasm  which  extend  to 
certain  bodies,  known  as  pyrenoids,  embedded  in  the 
chloroplasts.  When  a  filament  is  mounted  in  a  drop  of 
chloral  hydrate-iodine,  starch  is  found  to  be  clustered  about 
the  pyrenoids,  and  at  no  other  places  in  the  chloroplasts. 
We  may  conclude  from  this  that  while  the  chloroplast  is 
undoubtedly  manufacturing  food  throughout  its  whole 
body,  the  pyrenoids  are  the  centers  of  accumulation  of 
reserve  materials  in  the  form  of  starch  (Fig.  137).  When 
actively  growing  filaments  are  kept  in  the  dark  for  a  few 
days,  the  starch  disappears.  The  chloroplasts  utilize  the 
sunlight  in  the  same  manner  as  do  the  chloroplasts  in  the 


272 


Introduction  to  Botany. 


leaves  of  higher  plants.  The  student  may  be  able  to  per- 
ceive some  advantage  in  the  spiral  course  of  the  elongated 
chloroplasts  with  reference  to  the  absorption  of  light. 

All  cells  of  the  filamentous  individual 
perform  the  same  nutritive  functions ; 
any  one  of  them  may  take  part  in  the 
formation  of  spores ;  and  all  bear  prac- 
tically the  same  relation  to  the  outer 
world.  The  exterior  wall  of  the  filament, 
and  the  partition  walls  between  the  cells, 
are  of  cellulose,  and  permit  liquids  and 
gases  to  pass  readily  through  them. 
Since  they  possess  no  waterproof  cover- 
ing, the  filaments  quickly  dry  up  when 

taken  out  of  the 

_v water.        Being 

buoyed  up  by 
the  water  and 
freely  floating  in 
it,  very  little 
stress  is  ever 
exerted  on  the 
filaments,  and 
special  strength- 
ening devices 
are  unnecessary. 
165.  Repro- 
duction of  Spi- 


FiG.  137. 

v,  a  single  cell  of  Spirogyra,  showing  the  spiral  chloro- 
plasts containing  numerous  rounded  pyrenoids.  The 
nucleus  is  suspended  at  the  center  of  the  cell,  w  and 
x,  two  conjugating  filaments ;  at  i,  an  early  stage  in  the 
formation  of  a  connecting  tube  between  the  two  cells; 
at  2,  the  tube  has  formed  and  the  protoplast  from  a  cell 
of  filament  w  is  passing  into  the  corresponding  cell  of 
filament  x  and  is  fusing  with  its  protoplast ;  at  3,  a  later 
stage ;  at  4,  a  spore  has  formed  from  the  fused  proto- 
plasts. After  SACHS. 


rogyra.  —  Spirogyra  shows  a  degree  of  sexuality  in  the 
method  of  its  reproduction.  Two  filaments  which  happen 
to  be  lying  in  close  proximity  put  forth  outgrowths  from 
one  or  more  of  their  cells  which  finally  meet,  and  the  walls 
separating  them  become  absorbed.  The  entire  protoplast 


Algae,  Fungi,  and  Lichens.  273 

in  the  conjugating  cell  of  one  filament  passes  through  the 
tubular  connection  and  fuses  with  the  protoplast  in  the 
conjugating  cell  of  the  other  filament,  all  of  the  conjugat- 
ing cells  of  one  filament  being  receptive,  and  of  the  other 
contributive.  The  two  fused  protoplasts  organize  a  wall 
about  themselves,  and  become  a  resting  spore  which  is 
able  to  endure  desiccation  and  other  adverse  conditions. 
After  a  period  of  rest  the  spore  germinates  and  produces 
a  filamentous  individual  similar  to  those  from  which  it 
sprang  (Fig.  137).  The  filament  which  bears  the  spores 
may  be  considered  the  female  and  the  other  the  male,  but 
there  is  no  structural  differentiation  into  egg  and  sperm. 

166.  Vaucheria.  —  Vaucheria  is  a  filamentous  Alga  of 
another  character.     It  grows  either  in  water  or  on  moist 
and  shady  banks.     Each  individual  is  a  tubular  branched 
filament  which  in  its  vegetative  state  is  not  divided  by  cell 
walls.     One  end  of  the  filament  is  modified  in  such  a  way 
as  to  serve  as  an  anchor  to  the  substratum  (Fig.  138).     The 
protoplast  which  lines  the  tubular  filament  contains  many 
nuclei  and  probably  consists  of   many  fused  protoplasts. 
Small  rounded  chloroplasts  are  found  in  great  numbers  in 
the   filaments.      The  wall   is   of   cellulose  without   much 
waterproofing,  and  the  plant   cannot   flourish   away  from 
water  or  moist  places.     The  branched  filaments  have  the 
habit  of  interweaving,  and  so  furnish  each  other  mutual 
support. 

167.  Reproduction  of  Vaucheria.  —  Vaucheria  reproduces 
by  both  the  sexual  and  asexual  methods.      In  the  latter 
process  the  protoplasm  accumulates  in  a  swollen  end  of 
the  filament,  which  becomes  demarked  from  the  rest  of  the 
filament  by  means  of  a  transverse  wall.     The  swollen  end 
breaks  open  and  the  mass  of  protoplasm  passes  out  and 
swims  about  for  a  time  by  means  of  numerous  cilia  that 


274  Introduction  to  Botany. 

grow  out  over  its  surface.  Soon  it  comes  to  rest  and 
organizes  a  wall  over  its  surface,  and  after  a  brief  period 
it  germinates,  producing  a  new  branched  filament,  with  an 
expansion  at  one  end  for  anchorage  to  the  substratum. 

In  the  sexual  method  of  reproduction,  two  forms  of  out- 
growths are  produced  on  the  same  filament ;   a  rounded 


FIG.  138. 


Vaucheria  sessilis.  i,  a  filament-bearing  oogonia  (c)  and  an  Antheridium  (d). 
The  rounded  portion  to  the  left  represents  the  spore  from  which  the  filament 
has  sprung.  The  clear  branched  portion  is  a  clinging  organ  by  which  anchor- 
age is  made  with  the  substratum.  2,  a  germinating  spore.  3,  a  later  stage. 
4,  an  asexual  spore  escaping  from  its  parent  cell.  5,  the  same  after  it  has  come 
to  rest  and  surrounded  itself  with  a  cell  wall.  6,  the  spore,  (5)  in  the  first  stage 
of  germination ;  2  and  3  are  later  stages.  After  SACHS. 

one  (the  oogonium),  which  is  separated  from  the  parent 
filament  by  a  wall,  and  contains  the  egg,  and .  a  slender 
outgrowth  (the  antheridium\  containing  the  sperms  at  its 
apical  portion  (see  Fig.  138).  The  cells  containing  the 
egg  and  those  containing  the  sperms  break  open  at  their 
apices,  and  the  sperms  swim  out  by  means  of  two  cilia 


Algae,   Fungi,  and  Lichens.  275 

with  which  each  is  provided,  and,  seeking  the  egg,  one 
of  them  fuses  with  it  and  accomplishes  its  fertilization. 
However,  proterandry  may  occur,  so  that  the  egg  is  often 
not  fertilized  by  sperms  from  the  neighboring  antheridium. 
The  egg  while  still  contained  within  its  cell  then  produces 
a  thick  wall  about  itself,  and  passes  through  a  resting 
period  before  germinating.  Vaucheria  is  a  step  in  advance 
of  Spirogyra  in  the  evolution  of  sexuality,  for  its  repro- 
ductive elements  are  quite  sharply  differentiated  into  egg 
and  sperm. 

168.  Fucus.  —  The  large  brown  marine  Alga  known  as 
wrack-weed  or   bladder-wrack   (Fucus   vesiculosus)   grows 
anchored  to  the  rocks  between  high  and  low  tide  levels. 
Its   branches    are    somewhat   flattened,   and    possess    air 
bladders  which  buoy  it  up  in  the  water,  and  thus  enable 
it  to  expose  a  broad  surface  to  the  light.     It  is  multicellu- 
lar,  and  its  tissues  are  somewhat  differentiated,  the  central 
part  consisting  of  slender  cells  with  large  spaces  between 
them  containing  mucilage,   and  the  outer   tissues   being 
made  up  of  smaller  rounded  cells,  the   peripheral  layer  of 
which  has  the  nature  of  an  epidermis.     Chloroplasts  reside 
in  the  outer  tissues,  but  their  green  color  is  modified  by  a 
brown    coloring  matter  associated  with   the   chlorophyll. 
Notwithstanding  this,  the  chloroplasts  of  Fucus  are  active 
in   photosynthesis  and  sustain  the  same  relation  to   the 
sunlight  in  the  manufacture  of  food  materials  as  do  the 
chloroplasts  of  green  plants. 

169.  Reproduction  of  Fucus.  —  Reproduction  is  effected 
sexually  by  the  production  of  eggs  and  sperms,  borne  in 
minute  cavities  of  the  plant  body,  known  as  conceptacles 
(Fig.    139).      In  the  species  vesiculosus  the  sperms  and 
eggs  are  borne  in  different  plants,  but  in  other  species 
they  both    occur  in    the    same   conceptacle.      The   eggs, 


Introduction  to  Botany. 


eight  in  number,  are  borne  in  small  sacs  growing  out  from 
the  walls  of  the  conceptacle  (see  Fig.  139);  and  the 
sperms  are  formed  in  elongated  cells  produced  on  hair-like 
outgrowths.  Both  eggs  and  sperms  become  discharged 


FIG.  139. 

Fucus.  A,  portion  of  a  frond ;  B,  section  through  a  conceptacle ;  C,  oogonium 
with  eggs ;  D,  antheridium  with  sperm  cells ;  E,  an  egg  with  sperm  cells  swim- 
ming about  it.  After  THURET. 

from  their  conceptacles  into  the  surrounding  water,  and 
the  sperms  seek  the  eggs,  being  able  to  swim  about  by 
means  of  two  cilia.  One  of  the  sperms  penetrates  the  egg 
and  effects  its  fertilization.  The  egg  then  forms  a  wall 
about  itself  and  is  capable  of  immediate  germination. 

Some  of  the  marine  Algae  closely  related  to  Fucus  attain 
as  much  as  a  hundred  feet  in  length,  and  produce  lateral 


Algae,   Fungi,  and  Lichens.  277 

outgrowths  resembling  leaves  and  performing  the  functions 
of  leaves  ;  so  that  both  in  the  construction  of  the  vegetative 
parts  and  in  the  method  of  reproduction  we  find  in  them 
close  affinities  to  the  higher  plants. 

FUNGI. 

170.  Character  of  Fungi.  —  Turning  now  to  the  fungi, 
we  find  plants  which  are  characterized  by  their  lack  of 
chlorophyll,  and  a  consequent  inability  to  utilize  the  energy 
of  the  sunlight  in  the  manufacture  of  their  food.     We  find, 
therefore,  that  they  are  either  parasitic  or  saprophytic,  — 
that  is,  they  obtain  their  food  from  living  or  dead  plants 
or  animals.      They  are  closely  allied  to  the  Algae  in  their 
structure  and  modes  of  reproduction,   and  may  be  their 
degenerate  descendants. 

171.  Mucor,  or  Bread  Mould.  —  The  common  black  bread 
moulds,  Mucor  mucedo  and  Mucor  stolonifer,  are  good  repre- 
sentatives of  the  saprophytic  kinds  of  Fungi.     The  first- 
named  Mucor  is  composed  throughout  its  whole  vegetative 
body  of  a  much-branched  unicellular  filament  which  rami- 
fies  partly   through   the   substratum   and  partly  over  its 
surface,  forming  a  somewhat  felty  coating.     The  wall  of 
the  filament  is  thin  and  permits  the  transfusion  of  liquids. 
The  portion  of  the  Fungus  which  is  embedded  in  the  sub- 
stratum excretes  a  ferment  that  renders  organic  substances 
soluble  and  adapted   to  absorption  and  assimilation.      In 
this  way  the  Fungus  is  able  to  devour  the  starchy  and 
proteid  substances  of   bread,  vegetables,   fruits,  etc.,  and 
even  the  cellulose  composing  cell  walls.     Such  ferments 
are  extracted  in  large  quantities  from  Fungi  and  sold  on 
the  market  in  the  form  of  digestive  extracts  or  tablets. 

172.  Reproduction   of   Mucor.  —  Having   accumulated  a 
sufficient  amount  of  food  materials,  it  proceeds  to  form  its 


Introduction  to  Botany. 


reproductive  bodies.      Portions  of  the  branched  filament 
become  cut  off  by  cell  walls,  and  these  demarked  portions 


FIG.  140. 


Stages  in  the  life  history  of  Mucor  mucedo.  A,  an  entire  plant  bearing  sporangia 
on  upright  stalks.  B,  i  and  2,  a  sporangium  before  and  after  breaking  open  to 
discharge  the  ellipsoidal  spores;  3,  the  upper  part  of  the  stalk  after  the  sporan- 
gium has  broken  away ;  5,  a  germinating  spore  which  is  to  produce  a  plant  like 
A.  C,  i,  two  conjugating  branches  of  the  thread-like  mycelium  ;  2,  a  later  stage, 
showing  two  end  cells  demarked  by  cell  walls ;  3,  a  later  stage  where  the  wall 
separating  the  two  end  cells  from  each  other  has  become  dissolved,  so  that  the 
contents  of  the  two  cells  have  fused  to  form  a  resting  spore ;  4,  the  mature  rest- 
ing spore ;  5,  the  germinating  resting  spore  giving  rise  to  a  single  sporangium 
bearing  relatively  few  spores,  as  shown  in  B,  4.  After  BREFELD. 

send  forth  branches  which  grow  outward  from  the  sub- 
stratum, sometimes  to  a  distance  of  several  centimeters, 


Algae,  Fungi,  and  Lichens.  279 

and  finally  produce  enlargements  at  their  ends  which 
become  separated  from  the  rest  of  the  branch  by  a  cell 
wall  (Fig.  140).  The  protoplasm  in  these  enlarged  ends 
divides  into  many  spores,  which  finally  break  out  from  the 
surrounding  wall  and  become  scattered,  giving  rise  on  their 
germination  to  new  filamentous  individuals. 

When  the  substratum  supplies  an  abundance  of  food 
materials,  resting  spores  may  be  produced  sexually.  In 
this  process  the  ends  of  two  branches  meet,  and  a  partition 
wall  is  formed  in  each,  a  short  distance  back  from  the 
ends.  The  end  walls  then  become  dissolved,  and  the  con- 
tents of  the  short  terminal  cells  fuse  together,  thus  consti- 
tuting a  single  cell,  which  then  enlarges  considerably, 
produces  a  thick  outer  wall,  and  enters  into  a  period  of 
rest.  When  this  sexually  produced  spore  germinates,  the 
thick  outer  wall  becomes  broken,  and  the  inner  wall  and 
contents  grow  forth  and  produce  a  branched  filament 
which  sooner  or  later  gives  rise  to  asexual  spores  as  above 
described  (see  Fig.  140).  By  the  asexual  spores,  which 
are  produced  in  almost  countless  numbers,  the  fungus  be- 
comes broadly  scattered,  while  the  less  number  of  sexual 
spores  serves  to  carry  the  species  through  adverse  condi- 
tions. 

173.  Rusts.  —  The  rusts  on  wheat  and  other  grasses  are 
interesting  representatives  of  a  large  class  of  Fungi  which 
obtain  their  living  at  the  expense  of  other  live  plants. 
Observations  163  and  164  have  shown  us  that  the  rusty 
streaks  appearing  on  the  leaves  of  wheat,  for  instance, 
are  really  masses  of  the  oval  spores  of  the  fungus  (Fig. 
141,  A)  which  break  through  the  epidermis  and  become 
blown  about  by  the  wind.  The  spores  are  borne  on  the 
filamentous  vegetative  part  of  the  Fungus  (Fig.  141,  B), 
which  ramifies  amongst  the  parenchyma  cells  of  the  leaf 


280 


Introduction  to  Botany. 


and  appropriates  the  materials  manufactured  there.    These 
spores,  called  summer  spores,  or  uredospores,  when  brought 


A  FIG.  141. 

A,  clusters  of  uredospores  of  wheat  rust  breaking  through  the  epidermis  between 
the  parallel  veins  of  a  leaf  of  wheat.  B,  a  cross  section  through  one  of  the 
spore  clusters  of  A,  showing  the  uredospores  highly  magnified. 

to  other  leaves  by  the  wind,  put  forth  slender  sprouts  which 
enter  the  leaf  through  the  stomata,  and  thus  within  the 

leaf  new  rust  plants 
are  started,  which  in 
turn  produce  summer 
spores. 

Later  in  the  season 
spores  are  formed 
which  are  two-celled, 
pear-shaped,  and 
darker  in  color  (Fig. 
142) ;  these,  known 
as  the  winter  spores,  or 
teleutospores,  survive 

parasitized  by  Puccinia.    The  mycelium  of  the 

fungus  extends  through  the  leaf  and  bears  clus-        the    Winter,    and     the 
ters  of  teleutospores  at  the  upper  surface.  following;  Spring  ger- 

minate and  produce  filaments,  each  bearing  several  small 
spores  (Fig.  143)  which  may  grow  into  the  leaves  of  barberry 


FIG.  142. 

Photomicrograph  of  a  cross  section  of  a  grass  leaf 


Algae,  Fungi,  and  Lichens. 


281 


bushes  where  these  abound,  producing 
chains  of  spores,  termed  aecidiospores,  in 
cup-shaped  cases  (Fig.  144,  B).  These 
spores  become  discharged,  and  when  blown 
to  the  surface  of  a  leaf  of  wheat  they  grow 
into  it,  and  finally  summer  spores  appear  at 
the  surface  of  the  leaf,  as  already  described. 

It  appears,  then,  that  the  rust  of  wheat 
produces  three  kinds  of  spores  and  requires 
two  kinds  of  plants  to  run  the  full  course  of 
its  existence.  The  winter  spores,  however, 
can  establish  themselves  in  the  leaves  of 
wheat  without  the  intervention  of  the  bar- 
berry, and  the  summer  spores  can  also  sur- 
vive the  winter  and  reproduce  the  fungus 
on  wheat  the  following  spring. 

Other  parasitic  Fungi  of  common  occur- 
rence which  often  do  great  damage  to  the 
plants  of  the  field  and  garden  are  the 
srnuts  and  mildews. 


FIG.  143. 

Germinating  te- 
leutospore  of 
wheat  rust.  After 

TULASNE. 


FIG.  144. 


A,  leaf  of  barberry  bearing  aecidiospores  of  wheat  rust. 
B,  cross  section  through  the  barberry  leaf,  showing 
groups  of  spores  immersed  in  the  tissue  of  the  leaf.  (B 
after  DE  BARY.) 


174.      Toad- 
stools. —  The 

toadstools  are 
too  commonly 
observed  to  re- 
quire descrip- 
tion here,  and 
only  a  brief  ac- 
count of  their 
structure  and 
ways  of  life  will 
be  necessary. 
The  stem  and 


282 


Introduction  to  Botany. 


cap  are  com- 
posed of  multi- 
cellular  fila- 
ments so  closely 
woven  and 
grown  together 
as  to  form  a 
false  tissue  (Fig. 
145).  On  both 
surfaces  of  the 
gills  minute 
spores  are  borne 
which  become 
projected  to  the 
ground,  as 
shown  by  Obser- 
vation 167.  Or 
in  some  cases 

both  cap  and  stem  deliquesce,  form- 
ing a  fluid  mass  which  engulfs  the 
spores,  and  perhaps  assists  in  their 
germination.  When  the  substratum 
in  which  a  toadstool  is  growing  is 
carefully  dug  away,  it  is  found  that 
there  are  filamentous  growths  per- 
meating it  from  which  the  above- 
ground  part  of  the  Fungus  has 
sprung.  It  is  the  underground 
FIG.  145. 

Agaricus  campestris  or  mushroom.  D,  mature  plant  with  stalk  bearing  an  ex- 
panded cap,  from  which  gills  are  pendent.  G,  a  cross  section  of  some  of  the 
gills,  slightly  magnified,  and  F,  one  of  the  gills  in  cross  section  more  highly 
magnified,  showing  the  gill  to  be  fringed  on  both  surfaces  with  stalks  bearing 
spores.  H,  a  more  highly  magnified  detail  of  a  portion  of  F,  showing  the 
rounded  spores.  E,  young  mushrooms,  to  become  like  D.  After  SACHS. 


Algae,  Fungi,  and  Lichens. 


283 


FIG.  146. 


part  that  has  accumulated  the  food  necessary  to  main- 
tain the  very  rapid  growth  which  toadstools  are  so 
well  known  to  make.  The  student  will  notice  by  a 
careful  examination  of  the  sub- 
stratum that  it  is  very  rich  in 
vegetable  remains  in  the  form  of 
mouldering  leaves,  stems,  roots, 
etc.,  whose  substance  the  toad- 
stool is  able  to  digest  by  means 
of  ferments  excreted  from  its  un- 
derground filaments. 

But  the  toadstools  and  their  allies 
do  not  always  restrict  themselves 
to  this  innocent  mode  of  life,  for  it 
may  happen  that  underground  fila- 
ments, ramifying  through  the  rich 
mould  of  a  forest  in  quest  of  food, 
penetrate  the  roots  of  a  tree,  and  Destruction  by  Fungi  of  a  ceil 

.  of  pine  wood.  The  branched 

entering   the   WOody  tissues,  digest  filament  is  a  part  of  the  my- 

and    appropriate    them    for    food        ceiium  of  the  Fungus.   The 

upper  part  of  the  wood  cell 

(Fig.  146).  So  the  Fungus  advances 
deeper  into  the  roots,  and  up  into 
the  stem,  sapping  their  strength, 
until  the  tree  may  easily  be  broken 

off  or  upturned  by  the  wind.  These  Fungi  also  gain 
access  to  the  interior  of  the  trees  through  wounds  in 
the  bark,  or  through  the  broken  branches  of  the  above- 
ground  parts.  (Figure  147  shows  a  portion  of  a  trunk 
of  a  tree  which  has  suffered  from  the  ravages  of  Fungi.) 
In  some  localities  forest  trees  suffer  considerable  dam- 
age from  foes  of  this  kind;  and  not  only  trees,  but 
timbers  also  which  have  already  been  put  to  purposes  .of 
construction. 


has  not  yet  been  disinte- 
grated by  the  Fungus,  as  has 
the  lower  dotted  part.  After 
R.  HARTIG. 


284 


Introduction  to  Botany. 


Besides  multiplying 
by  spores,  the  toadstools 
may  be  disseminated  by 
the  separation  of  bits  of 
the  masses  of  filaments 
which  occupy  the  sub- 
stratum ;  in  this  way 
mushrooms  are  artifi- 
cially propagated. 

LICHENS. 

175.  Nature  of  Lichens. 
—  The  Lichens  afford  a 
unique  example  of  para- 
sitism by  Fungi ;  for  a 
Lichen  is  not  a  distinct 
plant,  but  rather  a  com- 
munity of  Fungus  and 
Algae.  The  little  Pleuro- 
coccus  with  which  we  are 

already  acquainted  is  often  associated  with  a  Fungus  in 

this   way.     The   Fungus 

undoubtedly    derives    its 

food  from  materials  man- 
ufactured by  the  Algae, 

but  at  the  same  time  it 

does  the  Algae  no  bodily 

harm,  except  that  which 

might  result  from  the  tax 

on  their  industry.     It  is 

thought    by    some    that 

there  is  a  fair  exchange 

of   benefits   between  the 


FIG.  147. 

Trunk  of  a  tree  in  process  of  destruction  by 
Fungi.  Fungi  belonging  to  the  genus  Poly- 
porus  growing  out  from  the  trunk.  Interior 
of  the  tree  rotten  and  hollow  and  used  as  a 
nest  by  owls. 


FIG.  148. 


Different  forms  of  Lichens. 
a,  Parmelia  colpodes ;  b, 
Graphis  scripta  on  bark  of 
tree ;  the  elongated  black 
spots  are  the  Lichens ;  c, 
Cladonia  furcata. 


Algae,  Fungi,  and  Lichens.  285 

Fungus  and  the  Algae,  the  Fungus  extracting  water  and 
salts  from  the  substratum  and  sharing  it  with  the  Algae ;  but 
it  must  be  remembered  that  the  Algae  are  able  to  flourish, 
perfectly  well  without  the  intervention  of  the  Fungi,  while 
those  Fungi  which  form  Lichens  are,  with  few  exceptions, 


FIG.  149. 

Section  through  the  fruiting  part  of  a  Lichen.  The  stratum  of  dark  rounded  bodies 
(h)  represents  the  algal  part  of  the  Lichen;  mt  the  thread-like  hyphae  of  the 
Fungus  constituting  the  bulk  of  the  body  of  the  Lichen ;  s  (at  the  top  in  one  of 
the  sacs),  sacs  or  asci  in  which  the  spores  of  the  Fungus  are  borne.  After 
SACHS. 

not  known  to  exist  without  the  assistance  of  the  Algae,  with 
which  they  associate  themselves.  Figure  148  shows  dif- 
ferent forms  of  Lichens,  and  Figure  149  represents  a  cross 
section  through  the  body  of  a  Lichen,  revealing  the  tissue 
formed  by  the  filaments  of  the  Fungus  and  the  embedded 
Algae. 


CHAPTER   XIII. 
MOSSES,  FERNS,  AND  HORSETAILS. 

PROVIDING  MATERIALS. 

Mosses  and  ferns  can  be  obtained  at  any  time  of  the  year  in  green- 
houses. The  prothallia  of  ferns  usually  grow  in  great  quantities  in  the 
shady  and  moist  soil  beneath  the  benches.  Mosses  may  also  be  found 
in  good  condition  in  the  shade  and  shelter  of  woods  in  early  spring  and 
summer,  and  even  in  the  winter  season,  in  some  localities.  When 
mosses  and  fern  prothallia  are  found  bearing  antheridia  and  archegonia, 
it  is  a  good  plan  to  lay  in  a  supply  in  formalin  or  70  %  alcohol.  Equi- 
setums,  or  horsetails,  should  be  gathered  in  fruiting  condition  in  early 
spring  and  summer,  and  preserved  dry  or  in  formalin.  Some  mosses, 
ferns,  and  horsetails  should  be  collected  in  the  fruiting  condition  and 
preserved  dry  for  experiments  with  the  spores. 

OBSERVATIONS. 
MOSSES. 

170.  Examine  mosses  in  their  natural  habitat     Separate 
a  single  plant  carefully  from  its  associates  and  from  the 
substratum.     What  is  the  character  of  the  members  which 
connect  it  to  the  substratum  ?     What  is  the  nature  of  the 
substratum  ;  is  it  moist  or  dry  ? 

171.  Examine  mosses  which  are  in  fruit.     The  fruiting 
stage  will  be  recognized  as  the  slender  stem  growing  from 
the  apex  of  the  leafy  stem  and  terminating  with  a  capsule 
which  bears  the  spores.     Examine  the  spore  capsules  of 
different  ages.     Notice  how  they  normally  break   open. 
Examine  the  opening  with  a  lens,  and  shake  out  some  of 
the  spores  and  examine  them  with  a  lens. 

286 


Mosses,  Ferns,  and  Horsetails.  287 

172.  Examine  with  a  lens  the  apices  of  some  of  the 
leafy  stems  which  are  not  bearing  capsules.     A  diligent 
search  is  likely  to  reveal  two  kinds  of  structures,  —  very 
small  flask-shaped  bodies,  termed  arcJiegonia,  which  bear 
the  eggs,  and  club-shaped  bodies,  termed  antheridia,  which 
contain  the  sperms.     Make  drawings  of  all  the  members 
thus  far  studied. 

173.  Mount   archegonia   and   antheridia   in  a  drop  of 
water  under  a  coverglass,  and  examine  with  medium  and 
high  powers.     Mount  and  examine,  in  the  same  manner, 
some  of  the  spores  contained  in  the  capsules.     Draw  as 
seen  with  both  low  and  high  powers. 

174.  Boil  pieces  of  soft  brick,  and,  after  cooling,  place 
them  in  a  dish  of  water  so  that  they  are  but  little  sub- 
merged.    Scatter  the  spores  over  the  brick,  cover  with  a 
bell  jar,  and  set  in  strong  diffuse  light,  but  not  in  direct 
sunlight.      When   delicate   green   filaments  (protonemata, 
singular  protonemd)  begin  to  appear  over  the  brick,  scrape 
off  some  of  them,  mount  in  a  drop  of  water  under  a  cover- 
glass,  and  examine  with  medium  and  high  powers.     Leave 
the  brick  under  the  bell  jar,  replenish  the  water  as  needed, 
and  observe  developments. 

175.  Remove  a  leaf  from  a  moss,  mount  in  a  drop  of 
water  under  a  coverglass,  and  examine  with  a  high  power. 
How  many  cells  thick  is  the  leaf?     What  is  the  form  of 
the  chloroplasts  ?     Are  stomata  present  ?     Place  a  drop  of 
chloral  hydrate-iodine  on  the  slip  in  contact  with  the  cover- 
glass,  and  draw  out  the  water  with  a  piece  of  filter  paper 
placed  against  the  opposite  edge  of  the  coverglass.     As 
the  chloral  hydrate-iodine  replaces  the  water,  watch  the 
effect  upon  the  chloroplasts.     Does  starch  appear  in  them  ? 
Do  plants  which  have  been  kept  in  the  dark  give  a  differ- 
ent result  ? 


288  Introduction  to   Botany. 

176.  Dig  up  a  clump  of  mosses  in  fruit,  and  place  it  in  a 
shallow  dish  containing  sufficient  water  to  keep  the  bottom 
of  the  clump  moist.     Cover  it  with  a  bell  jar,  and  after  a 
few  hours  remove  the  bell  jar  and  observe  the  behavior  of 
the  capsules  as  the  atmosphere  about  them  becomes  less 
humid. 

FERNS. 

177.  Examine  ferns  in  their  natural  habitat.     Note  ex- 
posure to  the  sun,  and  the  nature  of  the  soil, —  whether  it 
is  moist  or  dry.     Dig  up  a  plant  and  observe  the  character 
of  the  underground  parts. 

178.  Examine  the  back  of  the  leaves  for  the  rounded  or 
linear  clusters  (son,  singular  sorus)  of  sporangia.     Select 
a  portion  of  a  leaf  which  shows  by  the  brown  color  of  the 
sporangia  that  the  spores  are  ripe,  and  place  it  under  a 
bell  jar  on  a  piece  of  moist  white  filter  paper.     After  a  few 
hours  remove  the  bell  jar  and  examine  the  paper  with  a 
lens  to   see   whether  the  spores  have  become  scattered. 
Even  old  herbarium  specimens  might  answer  the  purpose. 

179.  Scatter  spores  over  pieces  of  brick  and  keep  moist 
under  a  bell  jar,  as  directed  for  the  spores  of  mosses.    After 
a  few  weeks  the  spores  should  have  germinated,  and  the 
green  bodies  resulting,  known  as  the  prothallia,  should  be 
examined  under  a  microscope.     How  are  they  anchored  to 
the  brick  ?     After  a  time  archegonia  and  antheridia  should 
be  observable  on  the  under  sides  of  the  prothallia.     Take 
care  of  the  experiment  until  young  fern  plants  begin  to 
grow  erect  from  the  prothallia. 

HORSETAILS. 

1 80.  Note  the  character  of  the  habitat  in  which  horse- 
tails flourish.     Dig  up  some  of  the  plants  and  observe  the 
nature  of  the  roots  and  the  relation  of  the  plants  to  each 


Mosses,  Ferns,  and  Horsetails. 


289 


other  by  means  of  the  underground  parts.  Examine  the 
cylindrical  stems.  Are  there  any  structures  growing  from 
the  nodes  which  may  be  morphologically  leaves  ?  Halve  a 
stem  longitudinally  from  top  to  bottom  and  note  its  con- 
struction. 

181.  Examine  the  spo- 
rangia which  are  borne  in 
cone-like  clusters  at  the 
tops  of  the  stems.  Scatter 
some  of  the  dry  spores  on 
a  glass  slip  and  examine 
with  a  medium  power. 
Gently  breathe  on  the  slip 
and  note  the  result.  Mount 
some  of  the  spores  in  a  drop 
of  water  under  a  coverglass 
and  examine  with  a  high 
power. 


FIG.  150. 


A,  entire  moss  plant,  the  leaf-bearing 
gametophyte  with  rhizoids,  bearing  the 
sporophyte,  i.e.  the  capsule  and  its  stem  ; 
o,  the  operculum,  which  falls  off  and  al- 
lows the  spores  to  escape ;  B,  the  cap- 
sule surmounted  by  the  calyptra  (c); 
C,  capsules  with  the  fringe  of  teeth  open 
and  closed.  In  part  after  KERNER. 


DISCUSSION. 
MOSSES. 

176.  Character  of  Mosses. 

-The  shoot  of  the  moss 

plant  is  differentiated  into 

stem  and  leaves  of  very  simple  construction.  Filamentous 
outgrowths,  called  rhizoids,  anchor  the  plant  to  the  sub- 
stratum, and  have  the  absorptive  function  of  the  roots  of 
the  higher  plants  (Fig.  150).  Because  of  their  simple  con- 
struction and  lack  of  an  effective  protection  against  too 
great  transpiration,  the  mosses  are  mostly  restricted  to 
moist  and  shady  situations,  although  some  species  occur 
in  exposed  localities,  having  acquired  the  power  of  reviv- 
ing after  long  periods  of  desiccation.  The  leaves  of 


290 


Introduction  to  Botany. 


mosses  perform  the  same  functions  as  do  those  of  higher 

plants. 

177.    Reproduction  of  Mosses.  —  An  examination  of  the 

apices  of  moss  shoots  reveals  the  fact  that  archegonia  and 

antheridia  (Fig.  151)  are  pro- 
duced there,  in  some  species 
both  on  the  same  plant,  and 
in  others  on  different  plants. 
The  archegonia  and  anther- 
idia are  small  and  obscure, 
and  would  be  overlooked  by 
the  casual  observer.  The  wall 
of  the  antheridium  breaks 
open  at  its  apex  (Fig.  151,  B\ 
and  the  sperms  (s  and  /) 
being  freed,  swim  about  in 
the  dew  or  rain  which  has 
collected  over  the  plants ;  and 
being  attracted  by  some  chem- 
ical substance  secreted  within 
the  archegonia  (Fig.  151,  A) 
they  enter  these  through  their 
FlG-  I5I-  hollow  apical  elongations,  and 

A,  archegonium  with  egg  cell  at  the  base  one  sperm  in  each  Case  f  USCS 

of  the  cavity,  and  B,  antheridium  of  a  •  i      -i 

moss.     At  j  and  t  are  sperms  ;  these  With  the  egg. 

are  seen  escaping  from  the  apex  of  B.  Tne  fertilized  egg  immedi- 
All  highly  magnified.     After  SACHS. 

ately  germinates  without  leav- 
ing its  position  in  the  archegonium,  and  the  rod-shaped 
embryo,  as  it  elongates,  breaks  off  the  narrow  upper  part 
of  the  archegonium  and  carries  it  as  a  sort  of  cap  called  the 
calyptra  (Fig.  150  B,  c).  At  the  same  time  the  lower  part 
of  the  embryo  pushes  its  way  down  into  the  tissues  of  the 
parent  plant,  from  which  it  continues  to  draw  food  until 


Mosses,  Ferns,  and  Horsetails.  291 

the  time  of  its  maturity ;  that  is,  until  the  capsule  contain- 
ing the  ripened  asexual  spores  has  been  formed  at  its  apex. 
The  asexual  spores  are  capable  of  germination  as  soon  as 
formed,  but,  instead  of  producing  a  leafy  moss  plant  imme- 
diately, they  first  form  filamentous  outgrowths  called  pro- 
tonemata,  resembling  the  filamentous  Algae  (Fig.  152,  A 
and  B\  Finally  buds  (Fig.  152,  B)  are  formed  on  the 
protonemata,  which  develop  into  the  leafy  moss  plant. 


FIG.  152. 

A,  germinating  moss  spore ;  B,  proionema  produced  by  further  development  of  A. 
To  the  left,  near  the  base,  is  a  bud  which  is  to  become  a  moss  plant.  After 
SACHS. 

The  life  history  of  a  moss  exhibits  an  alternation  of  two 
sorts  of  generations ;  the  leaf -bearing  generation,  with  its 
archegonia  and  antheridia,  known  as  the  sexual  generation, 
or  gametophyte,  and  the  leafless  asexual  generation,  or 
sporophyte,  namely,  the  capsule  and  its  stalk,  which  grows 
from  the  fertilized  egg  in  the  archegonium  and  produces 
spores  asexually.  It  should  be  observed  that  the  asexual 
generation  in  its  young  state  bears  chlorophyll,  and  must 
therefore  be  able  to  manufacture  a  portion  of  its  food, 
at  least  for  a  time. 

178.  Dissemination  of  Spores.  —  It  will  be  seen  that  after 
the  top,  or  operculum  (Fig.  150,  O\  of  the  sporangium  has 


292 


Introduction  to  Botany. 


broken  away  the  spores  are  still  kept  from  falling  out  by 
means  of  a  fringe  of  teeth  (Fig.  150,  C) ;  these  are  more  or 
less  hygroscopic  in  different  species. 
They  close  the  opening  of  the  cap- 
sule in  a  humid  atmosphere  and 
open  outward  to  allow  the  spores  to 
be  shaken  out  in  a  dry  atmosphere. 
The  winds  probably  dry  the  teeth 
and  shake  out  the  spores  at  the 
same  time. 

FERNS. 


FIG.  153. 


179.  Character  of  Ferns.  —  An 
examination  of  the  construction  of 
a  fern  shows  it  to  be  much  more 

Scolopendrium,  a  fern  bearing      highly  Organized  than  a  niOSS.      The 

oblong  clusters  of  sporangia    tissues  of  its  stem  and  leaves  are 

(sort,  singular  sorus} .    After       -i  •  rr  . .    .      i     .  r 

STRASBURGER.  differentiated  to  perform  separate 

functions,  as  we  have  seen  to  be  the 

case  in  the  higher  plants,  and  it  has  true  roots.  The  leaves 
not  only  perform  the  usual  photosynthetic  function  of 
green  leaves,  but  they 
may  also  bear  spores 
asexually  on  their  under 
surface  (Fig.  153);  and 
since  no  part  of  the  fern 
plant  bears  sperms  or 
eggs,  we  must  look  upon 
it  as  an  asexual  genera- 

r  IG.  I54« 

tion,      or      sporophyte, 

.  J  Cross  section  through  a  sorus  of  Scolopendnum. 

Which    in    the    moSS    we         a  and  d,  sporangia  containing  spores   (the 
Saw        tO        be         leafless         spore  is  the  unicellular  stage  of  the  gam eto- 

phyte)  produced  asexually ;  c,  the  protective 
(namely,       the       Capsule         covering  or  indusium.  After  STRASBURGER. 


Mosses,  Ferns,  and  Horsetails. 


293 


and  stalk  bearing  it)  and 
more  or  less  parasitic  on 
the  sexual  generation. 

180.  Reproduction  of 
Ferns.  —  The  sporangia 
(Fig.  1 54)  and  the  spores 
contained  in  them  are,  in 
some  of  the  ferns,  direct 
descendants  of  a  single 
epidermal  cell.  In  other 
ferns  they  originate  in 
several  cells  of  the  epi- 
dermis and  deeper-lying 
tissues.  When  the  spores 


FIG.  156. 


C,  archagonium  of  a  fern  with  its 
egg  cell ;  D,  an  antheridium  with 
sperm  cells ;  £,  an  empty  anther- 
idium ;  F  and  G,  motile  sperms. 
After  STRASBURGER. 


FIG.  155. 


F,  prothallium  orgametophyte  of  a  fern  seen  on 
its  under  surface.  The  hairs  are  the  rhizoids. 
At  a  are  archegonia,  at  b  antheridia.  G,  a 
prothallium  bearing  a  young  fern  plant  or 
sporophyte.  After  STRASBURGER. 

are  ripe,  the  sporangia  break  open 
elastically  on  imbibing  moisture 
and  throw  the  spores  to  some 
distance.  When  the  spores  ger- 
minate, they  do  not  immediately 
produce  the  fern  plant,  but  in- 
stead, a  small  thin  body  known 
as  the  prothallium  (Fig.  155), 
which  lies  flat  on  the  substratum. 
The  prothallium,  which  may  be 
a  centimeter  or  less  in  diameter, 
bears  qn  its  under  surface  eggs 
in  archegonia,  and  sperms  in 
antheridia  (see  Fig.  156). 

The  sperms  are  minute  ciliated  • 
bodies.  They  become  discharged 
from  the  antheridia  and  swim  in 
the  rain  water  or  dew  in  quest  of 
the  egg,  being   attracted  by  a 


294  Introduction  to  Botany. 

substance  secreted  within  the  archegonium.  After  fertiliza- 
tion, by  coalescence  with  a  sperm,  the  egg  begins  a  series 
of  divisions  resulting  in  the  formation  of  a  young  fern  plant, 
whose  leafy  stem  turns  upward  and  seeks  the  light,  and 
whose  root  turns  downward,  penetrating  the  substratum. 
The  prothallium  bears  the  sex  organs  and  constitutes  the 
sexual  generation.  It  contains  chlorophyll,  and  is  con- 
nected with  the  substratum  by  absorbing  hairs  called 
rhizoids,  and  is  able  to  sustain  an  independent  existence,  in 
some  instances  for  several  years. 

181.  Comparison  of  Asexual  and  Sexual  Generations. — 
We  note  that  while  the  sexual  generation  is  the  more  con- 
spicuous in  the  mosses,  it  becomes  subordinate  in  size  and 
differentiation  in  the  ferns.  In  this  respect  the  ferns  may 
be  looked  upon  as  intermediate  between  the  mosses, 
together  with  other  lower  plants,  and  the  Spermatophytes  or 
seed-bearing  plants.  In  the  Spermatophytes,  as  in  the 
ferns,  the  asexual  generation  is  the  more  highly  developed, 
the  sexual  generation  being  reduced  to  such  an  extent  that 
it  requires  good  powers  of  the  microscope  to  demonstrate 
it ;  while  the  asexual  generation  is  composed  of  leaf,  stem, 
root,  and  all  of  the  flower  up  to  a  certain  stage  of  its 
development. 

These  facts  can  be  summarized  and  compared  by  refer- 
ence to  the  diagrams  of  Figs.  157,  158,  159.  In  these 
figures  the  sporophyte  is  unshaded  and  the  gametophyte 
(after  the  germination  of  the  spore)  shaded.  The  fern  will 
be  considered  first,  since  in  it  the  distinction  between  sporo- 
phyte and  gametophyte  is  most  evident. 

When  the  fern  spore  (Fig.  157,  d)  germinates,  a  multi- 
cellular  body  (A)  is  produced  (prothallium)  bearing  sex 
organs,  namely,  archegonia  (a),  containing  each  an  egg 
cell,  and  antheridia  (£),  bearing  sperms.  Since  the  pro- 


Mosses,  Ferns,  and  Horsetails. 


295 


thallium  bears  the  sex  organs,  it  is 
rightly  called  the  sexual  genera- 
tion, or  gametophyte.  The  egg, 
having  been  fertilized  by  fusion 
with  a  sperm  (see  paragraph  180), 
undergoes  segmentation ;  and  the 
cellular  division  thus  begun  con- 
tinues indefinitely,  resulting  in  a 
conspicuous  fern  plant  (Fig.  157 
B,  e)  which  bears  spores  asexually. 
As  has  been  said,  the  fern  plant 
has  no  sex  organs,  and  is  there- 
fore called  the  asexual  generation, 
or  sporophyte. 

During  the  cell  divisions  which 
are  immediately  concerned  in  the 
formation  of  the  spore,  the  number 
of  the  chromosomes  entering  into 
the  constitution  of  the  nucleus  is 
reduced  by  one-half  (see  page  109 
for  a  description  of  cell  and  nuclear 
division),  so  that  the  spore  con- 
tains only  one-half  as  many  chro- 
mosomes as  do  the  cells  which  make 
up  the  body  of  the  fern  plant,  but 
precisely  the  same  number  as  the 
cells  of  the  prothallium  or  gameto- 
phyte. Therefore  we  look  upon 
the  spore  as  the  one-celled  stage 
of  the  gametophyte.  When  the 
nucleus  of  the  sperm  cell  fuses  with 
that  of  the  egg  cell,  the  number  of 
chromosomes  now  entering  into  the 


Diagrams  of  the  sporophyte  and 
gametophyte  of  a  fern.  The 
spore  d  produced  asexually  on 
the  fern  plant  e  (sporophyte) 
is  the  beginning  of  the  gameto- 
phyte. All  of  the  gametophyte 
produced  by  the  germination 
of  the  spore  is  shaded ;  all  of 
thesporophyte  is  left  unshaded. 
A,  the  prothallium  (gameto- 
phyte) bearing  an  archego- 
nium  (a)  with  its  egg,  and  an 
antheridium  (<$)with  its  sperms. 
The  fern  plant  e  grows  from  the 
fertilized  egg.  Bt  a  later  stage 
than  A. 


296 


Introduction  to  Botany. 


constitution  of  the  nucleus  of  the  fertilized  egg  is  doubled 

by  this  union,  so  that  the  fertilized 
egg  contains  the  same  number  of 
.  chromosomes  as  do  the  nuclei  of 
the  cells  which  make  up  the  body 
of  the  fern  plant  or  sporophyte 
springing  from  the  fertilized  egg. 
Therefore  we  look  upon  the  ferti- 
lized egg  as  the  one-celled  stage 
of  the  sporophyte. 

When  the  moss  spore  (Fig.  158, 
ri)  germinates,  a  multicellular  body 
is  produced  (protonema,  /)  from 
which  springs  the  moss  plant  (g) 
bearing  antheridia  (r)  and  arche- 
gonia  (s)  at  its  summit.  Evidently, 
therefore,  the  entire  body  resulting 
from  the  germination  of  the  spore 
is  the  gametophyte.  The  egg  after 
fertilization  produces  the  slender 
stalk  (/)  and  capsule  (m),  namely, 
all  of  the  unshaded  part  of  Fig. 
158,  B,  which  must  be  the  sporo- 
phyte, since  it  is  produced  in  the 
same  manner  (namely,  from  the 
fertilized  egg  within  the  archego- 
nium)  and  has  the  same  position 
in  the  life  cycle  as  has  the  fern 
plant  in  the  life  cycle  of  the  fern. 
It  is  true  that  the  stalk  and  capsule 
appear  to  be  an  organic  part  of  -the 
moss  plant,  but  from  the  evidence 
before  us  we  must  conclude  that 


FIG.  158. 

Diagrams  of  the  sporophyte 
and  gametophyte  of  a  moss. 
The  spore  n  produced  asexu- 
ally  in  the  capsule  m  (which 
with  its  stalk  /  is  the  sporo- 
phyte) is  the  beginning  of 
the  gametophyte.  All  of  the 
gametophyte  produced  by 
the  germination  of  the  spore 
is  shaded ;  all  of  the  sporo- 
phyte is  left  unshaded,  p  in 

A,  the  protonema  from  which 
springs    the    moss   plant  g 
(gametophyte  together  with 
/) ,  bearing  an  archegonium 
(s)  with  its  egg,  and  an  an- 
ther idium(r)  with  its  sperms. 

B,  a  later  stage,  the  capsule 
or  sporophyte  having  sprung 
from  the  fertilized  egg. 


Mosses,  Ferns,  and  Horsetails. 


297 


they    are    neither    more    nor    less    than    the    sporophyte 
parasitic  upon  the  gametophyte. 

We  see  that  in  pro- 
ceeding from  the  moss 
to  the  fern,  or  from  a 
lower  to  a  higher  type 
of  vegetation,  the  ga- 
metophyte becomes 
much  reduced  in  size 
and  complexity  of 
structure,  while  the 
sporophyte  relatively 
advances  in  these  re- 
spects (compare  shaded 
and  unshaded  portions 
of  Figs.  157-158). 
Turning  now  to  the 
Spermatophy tes  or  flow- 
ering plants,  the  most 
complex  and  special- 
ized of  plants,  and  the 
latest  product  of  plant 
evolution,  we  find  two 
kinds  of  spores  (read 
paragraph  142,  page 
201),  the  pollen  spores 
and  the  embryo  sac 
spore  within  the  ovule. 
The  fact  that  the  em- 
bryo sac  is  a  spore  is 
not  so  evident  from  its  appearance  as  from  its  behavior. 

In  tracing  the  life  cycle  of  a  fern  and  a  moss  we  began 
with  the  germination  of  the  spores,  and  we  shall  begin  at 


FIG.  159. 

Diagrams  of  the  sporophyte  and  gametophytes 
of  a  flowering  plant.  The  pollen  spore  (d) 
produced  asexually  on  the  plant  (sporophyte) 
is  the  beginning  of  the  male  gametophyte,  and 
the  embryo  sac  spore  m,  also  produced  asexu- 
ally on  the  sporophyte,  is  the  beginning  of 
the  female  gametophyte.  All  of  both  gameto- 
phytes (e  and  n)  produced  by  the  germination 
of  both  kinds  of  spores  is  shaded ;  all  of  the 
sporophyte  is  left  unshaded.  There  is  no  dif- 
ferentiated archegonium  and  antheridium  on 
the  gametophytes.  b  and  c,  later  stages  than 
a.  The  young  sporophyte  or  embryo  (0) 
has  sprung  from  the  fertilized  egg.  At/  is  the 
endosperm. 


298  Introduction  to  Botany. 

the  same  place  in  the  life  cycle  of  a  flowering  plant.  The 
pollen  spore  consists  of  a  single  cell  (Fig.  159,  d\  as  does 
the  spore  of  a  moss  or  fern.  We  find,  however,  that  after 
a  time,  and  even  before  it  is  discharged  from  the  anther, 
the  pollen  spore  has  become  two-celled  (e).  The  germina- 
tion of  the  spore  of  a  moss  or  fern  began  by  the  division 
of  its  single  cell,  one  cell  becoming  two,  two  becoming 
four,  etc.,  until  the  complete  gametophyte  is  formed ;  and 
we  may  conclude  from  this  that  the  division  of  the  pollen 
spore  is  the  beginning  of  its  germination  and  of  the 
formation  of  the  complete  gametophyte.  Following  the 
further  behavior  of  the  pollen,  as  described  on  page  166, 
we  find  that  after  it  has  been  transferred  to  the  stigma  its 
inner  wall  forms  a  tube  penetrating  to  the  ovule,  and  that 
one  of  its  two  cells  passes  through  the  tube  to  the  ovule, 
having  first  divided,  or  subsequently  dividing,  to  form  two 
cells,  one  of  which  fuses  with  and  fertilizes  the  egg  cell, 
and  for  that  reason  must  be  considered  a  sperm.  From 
this  we  are  led  to  the  conclusion  that  the  three  cells  result- 
ing from  the  germination  of  the  pollen  spore  constitute  a 
gametophyte.  The  great  elongation  of  the  inner  wall  of 
the  pollen  spore  producing  the  pollen  tube  does  not  have 
its  counterpart  in  the  germinating  spores  of  ferns  and 
mosses.  The  pollen  tube  functions  in  part  as  an  anther- 
idium,  although  being  apparently  not  its  homologue. 

The  behavior  of  the  embryo  sac  spore  will  now  be 
traced.  It  is  a  single  large  cell  (m)  which  never  becomes 
discharged  from  the  place  of  its  formation  within  the 
ovule.  Usually  before  the  descent  of  the  pollen  tube  its 
nucleus  divides  and  the  daughter  nuclei  continue  the 
process  of  division  until  eight  nuclei  have  been  formed, 
four  of  them  taking  position  at  the  micropylar  and  four  at 
the  opposite  end  of  the  embryo  sac  (n).  One  from  each 


Mosses,  Ferns,  and  Horsetails.  299 

of  these  groups  then  moves  toward  the  center  of  the 
embryo  sac  (see  Fig.  88),  and  the  two  fuse,  forming  one, 
which  by  repeated  division  gives  rise  to  the  endosperm 
tissue  of  the  seed.  A  plasma  membrane  is  organized 
about  each  of  the  remaining  nuclei  of  the  two  groups, 
including  with  each  some  of  the  cytoplasm  of  the  embryo 
sac,  thus  forming  definite  cells.  When  a  sperm  cell  leaves 
the  pollen  tube,  it  is  found  to  penetrate  and  fuse  with  one 
of  the  three  cells  at  the  micropylar  end,  resulting  in  its 
fertilization  and  subsequent  division  and  ultimate  forma- 
tion of  the  embryo  (<?)  within  the  seed.  We  may  conclude 
from  this  that  the  cell  with  which  the  sperm  fused  is  the 
egg,  and  that  it,  and  the  other  cells  resulting  from  the 
germination  of  the  embryo  sac  spore,  including  the  endo- 
sperm (/),  constitute  a  gametophyte,  which  has  no  differen- 
tiated archegonium.  As  has  been  said,  the  division  of  the 
fertilized  egg  results  in  the  formation  of  the  embryo  (o). 
This  is  an  early  stage  of  a  new  sporophyte,  and  we  may 
say  that,  just  as  in  the  case  of  the  ferns  and  mosses,  the 
fertilized  egg  marks  the  close  of  the  gametophyte  part 
and  the  beginning  of  the  sporophyte  part  of  the  life  cycle 
of  Spermatophytes.  The  sporophyte  part  of  the  life  cycle 
continues  through  the  germination  of  the  seed  and  on 
through  the  growth  of  the  plant  up  to  the  formation  of 
pollen  spore  and  embryo  sac  spore,  which  marks  the 
beginning  of  the  gametophyte  part  of  the  life  cycle. 

We  see  that  the  flowering  plants  have  two  sorts  of  game- 
tophytes,  —  male,  produced  by  the  germination  of  the  pollen 
spore,  and  female,  formed  by  the  germination  of  the  embryo 
sac  spore.  The  same  thing  is  true  of  the  Selaginellas 
(standing  in  the  scale  of  evolution  between  the  ferns  and 
flowering  plants),  in  which  the  microspores  produce  male, 
and  the  macrospores  female,  gametophytes  (see  page  202). 


300  Introduction  to  Botany. 

The  fact  that  an  alternation  of  sporophyte  and  gameto- 
phyte  occurs  in  the  life  cycle  of  plants  from  mosses  to 
flowering  plants,  that  homologous  members  can  be  traced, 
and  that  there  is  a  definite  law  of  progression,  —  namely, 
an  increase  in  the  sporophyte  and  a  decrease  in  the  gameto- 
phyte  (compare  shaded  and  unshaded  portions  of  Figs. 
157,  158,  159),  —  affords  important  evidence  of  a  common 
origin  of  these  different  classes  of  plants,  fitting  in  with 
geological  evidence  pointing  to  the  same  conclusion. 

HORSETAILS. 

182.  Character  of  Horsetails.  —  Horsetails,  or  Eqtiisetums, 
are  interesting  not  only  because  of  their  peculiar  form,  but 
because  they  are  the  sole  representatives  of  a  large  and 
ancient  group  whose  fossils  are  much  in  evidence  in  the 
coal  measures.     Like  the  ferns,  they  attain  in  the  tropics 
a  much  greater  size  than  we  are  accustomed  to  see  in  the 
temperate  zones.     The  cylindrical,  hollow,  green  stem  bears 
at  each  node  a  whorl  of  leaves,  which  are  united  into  a  tube 
at  their  bases.     The  leaves  are  much  reduced  in  size  and 
have  lost  the  normal  function  of  leaves,  the  photosynthetic 
function  being  performed  by  the  stems,  whose  exterior 
cells  are  well  supplied  with  chloroplasts,  and  whose  epi- 
dermis is  perforated  with  numerous  stomata.     The  surface 
of  the  stem  is  encrusted  with  silica,  which  gives  protection 
against  mechanical  injuries.     The  plants  occur  in  clumps, 
or  large  masses,  on  banks  and  in  low  places  near  streams 
or  pools,  their  gregarious  habit  being  largely  due  to  running 
underground  stems. 

183.  Reproduction  of  Horsetails.  —  Asexual  spores  are 
produced  at  the  apices  of  the  stems  in  sporangia  which 
are  borne  on  the  under  side  of  umbrella-like  leaves,  termed 
sporophylls,  aggregated  in  the  form  of  a  cone  (Fig.  160). 


Mosses,  Ferns,  and  Horsetails. 


301 


The  sporangia  split  open  after  the  manner  of  anthers 
and  the  spores  are  readily  shaken  out  by  the  wind.  The 
spore  is  peculiar  in  having  its  outer  coat  split  into  four 
ribbon-like  bands 
which  coil  and 
uncoil  with  the 
varying  humidity 
of  the  atmos- 
phere. On  dry- 
ing, the  bands 
uncoil,  and  on 
imbibing  mois- 
ture they  coil  up 
again.  Perhaps 
the  coiled  bands, 
when  they  come 
in  contact  with 
a  suitable  object, 
may  serve  to  an- 
chor the  spores 
in  a  moist  place 
where  the  con- 
ditions for  ger- 
mination are 
good ;  or  in  dry 
situations,  where 
the  bands  are  spread  out,  they  may  serve  as  sails  to 
catch  the  wind  so  that  the  spores  may  be  carried  to 
more  favorable  situations.  The  bands  may  also  prove 
useful  in  binding  several  spores  together ;  for  since  the 
spores  on  germinating  give  rise  to  prothallia  bearing 
only  eggs  or  sperms,  the  prothallia  being  dioecious,  it 
would  be  obviously  in  the  interest  of  the  fertilization 


FIG.  160. 

Equisetum  arvense.  C,  a  sterile  shoot ;  D,  fertile  shoots ; 
o  and  p,  clusters  of  sporangia ;  q  and  r,  sporophylls 
bearing  sporangia ;  s,  f,  and  u,  spores,  with  spiral  bands 
uncoiled  at  t  and  u ;  v,  tubers  on  the  underground  stem. 
After  WOSSIDLO. 


302  Introduction  to  Botany. 

of   the    eggs   for   several   spores   to   germinate   in   close 
proximity. 

As  in  the  case  of  the  ferns,  the  prothallium  or  sexual 
generation  is  relatively  small  and  inconspicuous,  while  the 
asexual  generation  constitutes  the  plant  proper  as  we  gen- 
erally recognize  it. 


CHAPTER   XIV. 

ADAPTATION  TO  ENVIRONMENT. 

OBSERVATIONS. 

182.  Examine  plants  which  grow  in  dry  regions;  note 
whether  much  or  little  branched,  the  form  and  texture  of 
the  leaves.     In  what  ways  is  rapid  transpiration  guarded 
against?      Are  there  any   parts  which  serve  for  storing 
water  ?     Where   are   the  chloroplasts  located  ?     If  these 
plants  were  removed  to  regions  of  abundant  rainfall,  would 
they  have  any  advantage  over  the  plants  of  that  region  ? 
Can  you  see  wherein  they  would  be  at  a  disadvantage  ? 

183.  Compare,   if    possible,   with  plants   native  to  salt 
marshes  or  to  alpine  or  polar  regions. 

184.  Examine  plants  growing  partly  submerged  in  the 
water,  such  as  water  lilies  or  Sagittarias.     In  what  way  do 
you  find  them  better  adapted  to  living  in  water  than  are 
plants  which  grow  on  the  land?     Would  they  be  at  any 
disadvantage  on  the  land?     If  so,  in  what  ways? 

185.  Make  cross  sections  of  the  stems  and  underground 
parts  of  water  lilies  and  Sagittarias,  and  note  how  the  air  is 
given  access  to  the  submerged  parts. 

1 86.  Examine  plants  such  as  Lichens,  Pleurococcus,  etc., 
growing  on  the  bark  of  trees.     Do  they  at  times  become 
quite  dry  ?     Have  they  special  devices  to  keep  them  from 
drying  up  ?     Pour  water  over  some  of  these  plants  which 
have  become  dry.     Do  they  quickly  absorb  it?     How  are 
they  adapted  for  the  rapid  absorption  of  water  ? 

303 


304  Introduction  to  Botany. 

187.  Weigh  a  piece  of  dry  Spanish  moss.  Dip  it  into 
water  for  a  moment  and  then  shake  and  filter  away  the 
water  which  clings  to  its  surface,  and  weigh  again.  Does 
it  absorb  water  quickly  enough  to  profit  much  by  the  rains 
which  fall  upon  it  ? 

DISCUSSION. 

184.  Advantages  of  Complex  Structure.  —  Under  normal 
conditions  of  soil  and  climate,  the  complex  body  which  we 
find  in  the  higher  plants  is  better  adapted  to  utilize  materi- 
als and  forces  than  the  plants  of  simpler  construction,  such 
as  mosses  and  Algae.     This  is  due  to  the  fact  that  the  dif- 
ferentiation of  the  plant  body  into  distinct  kinds  of  tissues 
has  permitted  division  of  labor,  so  that  one  part  of  the 
plant  may  rise  into  the  free  atmosphere  and  light,  and  ob- 
tain  to   best   advantage   what   they  have  to   offer,  while 
another  part  may  burrow  into  the  soil,  and  draw  from  its 
reservoirs  of  water  and  mineral  substances.     The  above- 
ground  parts  of  such  plants  are  protected  against  too  great 
transpiration  by  waterproof   outer  layers  of  cells  in  the 
form  of  epidermal  or  cork  tissues.     They  are  equipped  to 
withstand  the  stress  of  storms  by  strong  wood  and  bast 
tissues ;    and   the   relatively    long   distances   between   the 
aerial  and  subterranean  supplies  of  food  are  connected  by 
suitable  systems  for  transportation  (see  chapters  on  Roots, 
Stems,  and  Leaves). 

185.  Result  of  Unfit   Environment.  —  We   see   at   onoe 
how  well  adapted  these  plants  are  to  the  position  in  which 
we  find  them ;  but  if  they  were  submerged  in  water  they 
would  die.     The  waterproof  tissues  on  their  exterior  which 
are  so  beneficial  to  them  in  their  natural  habitat  would  pre- 
vent the  relatively  small  amount  of   oxygen  dissolved  in 
the  water  from*  being  taken  up  in  sufficient  quantities  to 


Adaptation  to  Environment.  305 

support  the  respiration  necessary  to  the  life  of  the  proto- 
plasts, and  the  plants  would  drown. 

But  beside  these  dying  plants  others,  native  to  the  water, 
would  be  thriving,  well  able  to  obtain  their  necessary  oxy- 
gen from  the  relatively  small  amount  in  the  water,  because 
their  bodies  (in  the  case  of  Ceratophyllum  and  Myriophyl- 
lum,  for  instance)  are  divided  into  slender  segments,  which, 
like  the  gills  of  a  fish,  expose  a  large  surface  for  absorp- 
tion ;  and  because  the  very  slight  amount  or  total  absence 
of  waterproofing  on  their  surfaces  permits  a  ready  inter- 
change of  gases. 

If,  however,  we  remove  the  water  plant  and  place  it  on 
the  land,  it  also  soon  dies ;  but  now  not  for  lack  of  oxygen, 
for  it  can  obtain  more  of  this  than  before,  but  for  lack  of 
sufficient  water,  since  the  plan  of  its  construction  which 
adapted  it  to  the  water  now  allows  it  quickly  to  dry  up. 
It  is  clear  from  these  illustrations  that  if  a  plant  is  to  suc- 
ceed in  life,  or  if  it  is  to  live  at  all,  it  must  be  adapted  by 
its  form  and  construction  to  the  habitat  in  which  it  finds 
itself. 

186.  Kinds  of  Habitats.  —  We  find  some  plants  living  in 
the  water,  others  on  the  land,  that  is,  with  roots  in  the  soil 
and  shoots  in  the  air ;  and  still  others  entirely  in  the  air 
without  connection  with  the  soil,  such  as  some  tropical 
orchids.  If  we  examine  any  one  of  these  classes  of  habi- 
tats, we  find  that  it  offers  wide  ranges  of  variation.  The 
water  may  be  deep  or  shallow,  still  or  running,  hot,  as  in 
hot  springs,  or  cold,  fresh  or  salt,  turbid  or  clear.  The 
soil  may  vary  greatly  as  to  its  chemical  composition  or 
physical  condition;  it  may  be  clayey,  loamy,  sandy, 
gravelly,  rocky,  etc. ;  it  may  contain  little  or  much  of  com- 
mon salt ;  it  may  be  warm  or  cold,  depending  in  part  on 
the  foregoing  conditions.  The  air  may  be  relatively  quiet 


306  Introduction  to  Botany. 

or  boisterous,  warm  or  cold,  humid  or  dry,  foggy  or  clear, 
and  rare  or  dense,  depending  on  elevation. 

Also  in  considering  the  environmental  conditions  to 
which  plants  must  become  adapted  we  must  take  account 
of  the  maximum,  minimum,  and  average  temperatures  for 
the  year ;  maximum,  minimum,  and  average  rainfall ;  time 
of  greatest  rainfall,  whether  during  the  growing  season  or 
during  the  period  of  vegetative  rest ;  the  direction  of  the 
prevailing  winds  and  their  maximum  and  average  forces ; 
and  of  the  intensity  and  quality  of  the  light  as  it  varies 
from  low  to  high  elevations,  and  from  the  equator  to  the 
poles.  Indeed,  the  conditions  appear  to  be  too  numerous 
and  varied  for  us  to  assign  to  each  its  proper  value ;  but 
plants  feel  the  influence  of  each  factor  and  accommodate 
themselves  to  it.  We  shall  here  discuss  simply  the  main 
factors  with  which  plants  have  to  deal,  —  namely,  water 
supply,  light,  temperature,  atmosphere,  soil,  and  relation 
to  animals  and  to  other  plants. 

187.  Water   Supply.  —  Variations   in   the  water   supply 
are  more  effective  in  requiring  adaptive  changes  in  the 
forms  and  construction  of   plants  than  variations  in  any 
other  factors  (see  pages  37  and  1 10,  for  a  discussion  of  the 
value  of  water  to  plants).     When  there  is  plenty  of  water 
available  in  the  soil,  but  not  to  the  extent  of  saturation,  we 
find  plants  much  branched  above  and  below  ground,  with 
a  large  expanse  of   leaf   surface;    the  stomata  occur  fre- 
quently on  both  sides  of  the  leaf,  but  the  greater  number 
usually  occur  on  the  under  side.     The  great  majority  of 
plants  in  regions  having  a  temperate  climate  and  abundant 
rainfall  are  of  this  character. 

188.  Effect  of  Scarcity  of  Water.  —  A  scarcity  of  water 
necessitates  certain  profound  changes  from  this  type  which 
are  designed  to  reduce  transpiration ;  for  if  plants  are  un- 


Adaptation  to  Environment.  307 

• 
able  to  absorb  much  water,  it  would  be  fatal  to  them  to 

permit  rapid  transpiration.  Accordingly  we  find  under 
these  circumstances  a  diminution  in  the  transpiring  surface 
by  a  reduction  in  the  number  and  extent  of  the  branches 
and  leaves,  as  in  the  case  of  cacti,  for  example.  There  is 
also  usually  an  increase  in  the  thickness  and  waterproofing 
qualities  of  the  outer  wall  of  the  epidermis,  a  restriction  of 
the  stomata  to  the  under  sides  of  the  leaves,  a  depression 
of  the  stomata  below  the  surface  of  the  leaf,  as  in  the 
leaves  of  the  India  rubber  tree,  a  reduction  in  the  size 
of  the  intercellular  spaces,  and  frequently  the  above- 
ground  parts  are  covered  with  hairs,  scales,  etc.,  which 
retard  transpiration  and  reduce  the  intensity  of  illumina- 
tion. There  is  also  frequently  an  occurrence  of  specialized 
cells  and  tissues  for  the  storage  of  water,  and  of  cells  con- 
taining mucilage,  which  assists  in  retaining  water  within 
the  plant. 

189.  Conditions  affecting  Absorption.  —  There  are  certain 
conditions  under  which  plants  absorb  water  with  difficulty 
even  when  it  is  present  in  abundance.     Thus,  if  there  is  a 
large  percentage  of  salts  dissolved  in  the  water,  or  a  large 
amount  of  humic  acid  produced  by  the  disintegration  of 
organic  remains,  as  in  peat  bogs ;  or  if  the  soil  and  soil 
water  are  cold,  plants  absorb  the  water  with  great  difficulty. 
Under  such  circumstances  they  must  be  modified  to  reduce 
transpiration  just  as  if  little  water  were  present. 

190.  Effect  of   Submergence  in  Water.  —  We  find  quite 
another  class  of    modifications  in  those  plants  which  are 
rooted  in  earth  saturated  with  water,  such  as  the  mud  at 
the  bottom  of  ponds,  etc.     In  these  plants  there  is  not  so 
much  need  of  retarding  transpiration,  but  access  of  air  to 
the  submerged  parts  must  be  provided  for.     Accordingly 
we  find  the  stomata  nearly  all  transferred  to  the  upper  side 


308  Introduction  to  Botany. 

» 
of  floating  leaves,  such  as  those  of   the  water  lily,  and  a 

large  increase  in  the  extent  of  the  intercellular  spaces  for 
the  conduction  of  air  from  the  leaves  through  the  stems 
into  the  underground  parts. 

In  plants  entirely  submerged  in  the  water  we  usually  find 
the  stems  and  leaves  very  much  branched  for  the  purpose  of 
exposing  a  large  surface  for  the  absorption  of  oxygen  and 
carbon  dioxide  from  the  water,  and  at  the  same  time  there 
is  a  reduction  in  or  an  entire  obliteration  of  the  roots,  since 
such  plants  throughout  their  whole  surface  can  absorb 
whatever  the  water  affords  them.  There  is  also  a  re- 
duction in  the  amount  of  waterproofing,  a  diminution  or 
disappearance  of  the  stomata,  and  a  decrease  in  the  water- 
conducting  elements. 

191.  Light.  —  Although  light  is  quite  as  important  as 
water  for  the  life  of   the  higher  independent  plants,  the 
variations  in  its  quality  and  intensity  over  the  earth  are 
not  so  great  as  to  cause  or  to  require  the  profound  modi- 
fications which  we  find  produced  by  variations  in  the  water 
supply.     It  is  a  commonly  observed  fact  that  plants  which 
sprout  in  cellars  have  long  internodes  and  reduced  leaves. 
Experiments  have  shown  that  if  the  intensity  of  the  light 
be  increased  up  to  a  certain  point,  the  size  of   the  leaves 
produced   increases ;    but   that   passing   above   a   certain 
degree  of  intensity  of  illumination  the  leaves  attain  a  less 
and  less  size. 

192.  Effect  of  Dim  Light.  —  Experiments  with  Scolopen- 
drium   officinarum    showed   that   in   the  dark  the   leaves 
reached  a  length  of  76  millimeters  and  a  breadth  of  n 
millimeters  (Fig.  161,  i),  while  in  a  light  about  one-eighth 
as  intense  as  direct  sunlight   the  leaves  grew  to  be  228 
millimeters  long  and  25  millimeters  broad  (2);  and  in  a  still 
stronger  light  having  about  one-third  the  intensity  of  full 


Adaptation  to  Environment. 


309 


sunlight  the  leaves  attained  a  size  of   152  millimeters  in 
length  and  20  millimeters'  breadth  (3). 

Sempervivum  tectorum,  which  grows  naturally  in  sunny 
situations,  and  bears  fleshy  leaves 
in  rosettes  near  the  ground,  is 
considerably  modified  when 
grown  in  a  light  about  one-sixth 
as  strong  as  direct  sunlight. 
Under  this  condition  the  inter- 
nodes  elongate  so  that  the  ro- 
sette grouping  of  the  leaves  is 
lost,  the  leaves  formed  are 
smaller,  and  the  amount  of  chlo- 
rophyll is  less. 

We  can  see  that  some  of  the 
changes  in  habit  here  recorded 
are  directly  adapted  to  the  vari- 
ations in  the  intensity  of  illumi- 
nation. In  a  very  dim  light  it 
is  advantageous  to  the  plant  to 
lengthen  the  internodes  at  the 
expense  of  all  other  parts,  so  that 
the  leaves  may  more  surely  and 
quickly  be  brought  into  places  of 
greater  illumination.  Another 
directly  adaptive  effect  due  to  variations  in  light  intensity 
is  the  production  of  chloroplasts  nearer  the  surface  in 
dimly  lighted  situations.  This  is  well  illustrated  by  our 
wild  Smilaxes,  which  grow  in  the  shade  of  woods,  and  have 
chloroplasts  in  the  cells  of  the  epidermis  where  they  can 
absorb  the  dim  light  to  best  advantage. 

193.    Effect  of  Intense  Illumination.  —  Plants  may  adapt 
themselves   to   varying   degrees    of    illumination    in   still 


FIG.  161. 


%  full  sunlight  ;  3,  grown  in  %  full 


jio  Introduction  to  Botany. 

another  way.  Plants  of  the  same  species  growing  at 
progressively  higher  elevations  on  the  mountains  may 
produce  in  the  cells  of  the  epidermis  and  deeper-lying 
tissues  more  and  more  of  a  red  coloring  matter,  which 
evidently  serves  the  purpose  of  cutting  off  a  part  of  the 
light,  whose  intensity  increases  with  the  altitude  to  such 
an  extent  as  to  prove  destructive  to  the  chlorophyll. 
When  plants,  particularly  those  of  prostrate  habit,  grow 
in  shady  places,  the  red  color  is  apt  to  occur  in  the  lower 
epidermis,  and  appears  to  serve  the  purpose  of  arresting 
the  light  which  has  passed  the  upper  tissues,  reflecting 
part  and  transforming  part  into  energy  of  heat.  Intense 
illumination  seems  also  to  give  rise  to  the  production  of 
hairs,  scales,  etc.,  that  reflect  part  of  the  light,  and  also 
reduce  transpiration,  which  the  intense  illumination  tends 
to  accelerate. 

194.  Temperature.  — Variations  in  temperature  may  exert 
a  very  marked  influence  on  the  processes  of  nutrition  and 
growth,  and  therefore  on  the  size  of  plants ;  but  no  visible 
adaptive  changes  in  form  and  structure  are  known  to  be 
brought  about  solely  by  exposure  to  different  temperatures. 
On  the  contrary  it  frequently  happens  that  the  plants  of 
the  polar  regions  or  cold  mountain  peaks  have  the  same 
general  appearance  and  construction  as  those  of  hot  deserts. 
But  although  different  degrees  of  heat  may  not  give  rise  to 
adaptive  changes  in  form,  they  do  produce  very  radical 
adaptive  alterations  in  the  qualities  of  the  protoplasts,  for 
it  is  well  known  that  plants   of  tropical  and  temperate 
regions  would  quickly  succumb  to  the  low  temperatures 
which  plants  of  polar  regions  are  known  to  endure. 

195.  Resistance  to  Cold. — The  plants  of  the  Siberian  for- 
ests, for  example,  withstand  temperatures  as  low  as  60°  C. 
(76°  F.)  below  zero.      Kjellman,  the  botanist  of  the  Vega 


Adaptation  to  Environment.  311 

Expedition,  relates  the  following  remarkable  instance  of 
resistance  to  cold  by  Cochlearia  fenestrata,  a  member  of 
the  mustard  family,  shown  in  its  natural  size  by  Fig.  162. 
The  cold  was  very 
persistent,  and  of- 
ten fell  lower  than 
46°  below  zero,  Cen- 
tigrade. The  plant 
in  question  grew 
upon  the  summit  of 
a  rather  high  sand 
hill  near  Pitlekai, 

exposed  to  the  continuous  and  sharp 
north  and  northeast  winds.     It  began 
to  bloom  in  the  summer  of  1878,  but 
its  full  quota  of  flowers  was  far  from 
complete    when    winter    arrived    and 
stopped  its  further  development, 
the  inflorescence  then  consisting 
of  flower  buds  in  different  stages 
of    development,    newly    opened 
flowers,  faded  flowers,  and  more 
or   less   ripened   fruit.      There 
were  only  a  few  shriveled  re- 
mains of   the  basal  rosette  of   1  FIG.  162. 

leaves,     but     the     Upper     leaves     Cochlearia  fenestrata,  natural  size. 

were  alive  and  fresh.     In  this  After  KJELLMAN. 

condition  the  plant  was  over- 
taken by  winter  and  exposed  to  its  full  severity.  One 
might  expect  it  to  be  destroyed  under  such  circumstances, 
but  this  was  not  the  case;  for  when  the  summer  of  1879 
began,  the  plant  resumed  its  development  where  it  left  off 
at  the  beginning  of  winter :  the  flower  buds  unfolded  and 


312  Introduction  to  Botany. 

new  inflorescences  arose  in  the  axils  of  the  fresh  upper 
leaves. 

In  this  instance,  there  is  no  special  device  to  protect 
the  plant  against  the  cold,  and  its  power  of  resistance  ap- 
pears to  be  due  solely  to  the  character  of  the  protoplasts. 

Another  striking  instance  of  the  adaptation  of  the  proto- 
plasts to  low  temperatures  is  furnished  by  the  small  and 
delicate  alpine  Soldanellas.  These  lie  buried  in  the  snow 
during  the  winter ;  but  when  the  summer  sun  first  melts 
the  upper  layers  of  snow,  and  the  percolating  water 
moistens  the  earth  beneath,  the  flower  buds  of  the  Solda- 
nellas begin  to  spring  forth,  although  the  earth  and  water 
and  the  air  filling  the  interstices  of  the  snow  must  be  near 
the  freezing  point.  As  growth  continues,  a  part  of  the 
reserve  materials  stored  in  the  prostrate  leaves  and  subter- 
ranean rootstock  is  used  in  the  formation  of  new  tissues, 
and  a  part  is  united  with  oxygen  in  the  process  of  respira- 
tion, producing  heat  which  melts  the  snow  immediately 
above  the  flower  buds,  thus  enabling  them  to  unfold  above 
the  surface.  Sometimes  the  buds  blossom  out  while  still 
imprisoned  beneath  the  snow  (Fig.  163). 

196.  Resistance  to  Heat.  —  The  plants  of  deserts  and 
regions  of  high  temperatures  show  no  modifications  of  form 
which  are  directly  adaptive  to  heat  alone,  but  they  are  able 
to  withstand  very  high  temperatures  because  of  the  nature 
of  their  protoplasts.  At  Lahore  and  Multan,  India,  the 
maximum  temperatures  are  respectively  50.9°  and  52.8°  C. 
(123.6°  and  127°  F.),  and  in  the  sun  probably  from  63°  to 
70°  C.  (145.4°  to  158°  F.);  and  the  plants  of  those  regions 
have  of  course  become  adapted  to  these  extremes.  At 
some  places  near  the  equator  the  soil  temperature  is  known 
to  have  risen  to  80°  C.  (176°  F.),  and  in  one  instance 
even  to  84°  C.  (183.2°  F.).  A  species  of  Ipomoea  has  been 


Adaptation  to  Environment. 


313 


found  in  bloom  where  the  surrounding  soil  had  a  tempera- 
ture of  69°  C.  (156.2°  F.). 

Regarding  the  adaptation  of  plants  to  various  degrees  of 
heat,  the  general  statement  may  be  made  that  nowhere  on 
the  earth  is  it  too  cold  and  nowhere  too  hot  (except  at  the 
mouths  of  volcanoes,  etc.)  for  plants  to  live  and  grow,  in 
virtue  of  the  adaptive  capacity  of  their  protoplasts. 


FIG.  163. 

Alpine  Soldanellas  growing  through  the  snow.    After  KERNER. 

197.  The  Atmosphere.  —  Variations  in  the  pressure  of 
the  atmosphere,  so  far  as  artificial  experiments  teach  us, 
bring  about  marked  adaptive  modifications.  As  the  pres- 
sure is  diminished,  the  rate  of  growth  increases,  more 
numerous  branches  are  produced,  and  the  leaves  are  larger. 
These  changes  apparently  bear  a  direct  relation  to  the 
diminished  amount  of  oxygen ;  for  just  as  animals  must 
breathe  faster  at  high  elevations  where  the  atmosphere  is 


314  Introduction  to   Botany. 

rare,  so  plants  may  be  expected  to  have  need  under  like 
circumstances  of  increasing  their  surfaces  for  the  more 
rapid  absorption  of  oxygen.  But  in  nature,  at  high  eleva- 
tions, there  are  many  circumstances  which  must  be  taken 
into  account  by  plants.  The.  rarefaction  of  the  atmosphere 
increases  illumination,  radiation,  and  transpiration,  and 
these  circumstances  tend  to  modify  the  influence  of 
decreased  pressure. 


FIG.  164. 

Showing  the  north  slope  (on  the  right)  of  a  hill  densely  wooded,  while  the  south 
slope  (on  the  left),  which  is  exposed  to  the  drying  summer  winds,  is  destitute  of 
trees. 

198.  Effect  of  Winds.  —  The  wind  has  much  to  do  in 
determining  the  kinds  of  plants  which  shall  grow  in  a  wind- 
swept locality,  and  the  wind  also  brings  about  adaptive 
changes  by  causing  a  diminished  growth  of  the  plant  as  a 
whole,  and  notably  of  the  leaves ;  but  these  modifications 
are  probably  brought  about  indirectly  through  the  increase 
in  transpiration  caused  by  winds.  Instances  are  common 
where  the  windward  side  of  a  hill  is  nearly  or  quite 
destitute  of  trees,  being  clothed  merely  by  low-growing 
herbs,  grasses,  and  shrubs  (Fig.  164). 


Adaptation  to  Environment.  315 

We  have  already  seen  in  the  chapters  on  Flowers  and 
Dispersion  of  Seeds  how  adaptive  modifications  have  enabled 
plants  to  employ  the  wind  in  the  scattering  of  pollen  and 
seeds.  Plants  with  these  modifications  are  more  apt  to 
abound  in  windy  situations. 

199.  The  Soil.  —  The  different  kinds  of  soils  affect  the 
form  and  structure  of  plants  chiefly  in  the  capacity  of  soils 
as  water  reservoirs.     Coarse-grained  soils  with  large  inter- 
stices allow  the  water  to  percolate  readily  through  them, 
and  retain  but  little  for  the  use  of  plants.     Accordingly, 
plants  which  inhabit  such  soils  must  be  modified  so  as  to 
reduce  transpiration  and  to  store  water.     On  the  other 
hand,  soils  which  are  fine-grained,  and  particularly  such  as 
are  rich  in  clay  or  humus,  hold  large  percentages  of  water, 
and  the  plants  growing  in  them  are  not  so  apt  to  possess 
special  devices  to  restrict  transpiration. 

200.  Effect  of  Excess  of  Salts.  —  If  large  percentages  of 
soluble  salts  occur  in  the  soil,  they  influence  the  osmotic 
conditions  and  render  the  absorption  of  water  by  the  roots 
more  difficult ;  and  it  may  happen  in  such  cases  that  even 
with  plenty  of  water  at  hand  plants  may  be  in  danger  of 
drying   up.     The   same  sorts  of    adaptive    modifications, 
designed  to  retard  transpiration,  as  we  find  occurring  when 
the  soil  is  dry,  are  accordingly  brought  about. 

201.  Other   Plants   and    Animals.  —  In    the    preceding 
chapters,  numerous  illustrations  of  modifications  which  are 
adaptive  to  animals  and  to  other  plants  have  already  been 
discussed.     The  student  may  refer  to  the  modifications  of 
leaves  to  serve  as  traps,  of  stems,  roots,  and  leaves  for 
purposes  of   climbing,  of  flowers,  fruits,  and   seeds,   for 
the  dispersion  of  pollen  and  seeds  by  means  of  insects  and 
other  animals.    The  discussion  of  parasitic  roots  in  Chapter 
III,  and  of  Fungi  and  Lichens  in  Chapter  XII,  has  called 


Introduction  to  Botany. 

attention  to  parasitic  habits  of  life  ;  and  now  an  instance  of 
another  character  will  be  given  to  illustrate  the  sharp 
competition  which  is  so  common  among  plants. 


FIG.  165. 

Photograph  of  Sicyos  angulatus  clambering  over  undershrubs  in  the  foreground  and 
over  willow  trees  in  the  background.  The  plant  is  bedecked  with  its  clusters  of 
white  flowers. 

The  one-seeded  bur  cucumber,  Sicyos  angulatus,  has  had 
certain  of  its  branches  modified  in  the  form  of  tendrils 
which  are  so  sensitive  to  contact  that  when  they  touch  the 
branches  of  other  plants  they  twine  about  them,  drawing 


Adaptation  to  Environment.  317 

the  coils  tight  to  obtain  a  firm  hold.  In  this  way  this 
plant  is  enabled  to  reach  the  tops  of  trees  and  spread 
itself  out  over  their  crowns ;  or  it  may  cover  the  tops  of 
thickets  of  undershrubs,  greatly  to  its  own  advantage  in 
obtaining  light.  The  tendrils  are  so  quick  to  take  ad- 
vantage of  any  suitable  object  of  support  that  within  a  few 
minutes  after  they  have  perceived  its  presence  by  contact 
with  it  they  may  have  made  at  least  one  turn  about  it. 
Figure  165  shows  undershrubs  in  the  foreground,  and  wil- 
lows in  the  background,  almost  completely  hidden  by  the 
foliage  and  white  flowers  of  this  plant,  demonstrating  how 
efficiently  it  has  employed  its  method  of  using  other  plants 
as  supports. 

202.  Protective  Adaptations.  —  Factors  in  the  environ- 
ment which  are  a  source  of  danger  to  plants  have  resulted 
in  adaptive  modifications  of  various  sorts.  Not  infre- 
quently branches  and  leaves  become  modified  to  form 
spines  which  may  serve  as  a  means  of  protection  against 
marauding  animals.  In  desert  plants,  such  as  the  cacti, 
whose  succulent  tissues  are  greedily  sought  by  animals, 
these  modes  of  protection  are  of  vital  importance.  Still 
other  plants  find  protection  in  bitter  and  poisonous  se- 
cretions. 

One  of  the  most  wonderful  devices  to  secure  protection 
against  the  destruction  of  leaves  by  leaf-cutting  ants  is 
found  in  the  Brazilian  tree,  Cecropia  adenopus.  When  one 
shakes  the  tree,  an  army  of  ants  pours  forth  from  small 
openings  in  the  branches  and  makes^  a  vicious  attack  on 
the  intruder.  These  are  the  most  warlike  of  known  ants, 
and  their  bite  is  very  painful.  Their  chief  service  to  the 
tree  is  the  prevention  of  the  depredations  of  leaf-cutting 
ants,  which  abound  in  these  regions  and  are  wont  to  strip 
the  leaves  of  unprotected  trees  clean  to  the  midrib,  carry- 


318 


Introduction  to  Botany. 


ing  the  pieces  to  their  nests  for  the  purpose  of  working 
them  into  a  pulp  which  they  plant  with  a  certain  kind  of 
fungus,  constituting  their  chief  or  sole  food.  Figure  166 

shows  the  way  in  which 
these  ants  destroy  the 
leaves. 

The  soldier  ants  that 
protect  the  Cecropias 
against  the  leaf-cutting 
species  do  not,  however, 
serve  without  pay,  for 
these  trees  provide 
them  with  both  food 
and  shelter.  The  Ce- 
cropia  branches  are  hol- 
low at  the  center,  the 
cavity  being  divided  by 
numerous  cross  parti- 
tions (Fig  167,  A).  Just 
above  the  axils  of  the 
leaves  are  thin  places 
(Fig.  167  B,  a)  in  the 
stem  where  the  tissues 
are  lacking  in  woody 
elements  and  are  easily 
cut  through  by  the  ants.  The  ants  also  find  no  difficulty 
in  perforating  the  cross  partitions  so  that  they  can  pass 
from  chamber  to  chamber.  The  food  provided  for  the 
ants  is  produced  at  the  bases  and  under  sides  of  the 
petioles  in  the  form  of  minute  egg-shaped  bodies,  rich  in 
proteids  and  fats.  These  bodies  are  renewed  as  often 
as  the  ants  remove  and  carry  them  to  their  nests  (see 
Fig.  168). 


FIG.  166. 

f,  leaf-cutting  ants  walking  off  with  their  plun- 
der; K,  a  leaf  showing  damage  from  leaf-cut- 
ting ants.  After  A.  MOLLER. 


Adaptation  to  Environment. 


The  adaptive  modifications  of  the  Cecropia  having  a 
bearing  solely  on  the  problem  of  protection,  are  the  thin 
places  through  which  the  ants  burrow  an  entrance,  and  the 
never  failing  supply  of  food 
at  the  bases  of  the  petioles. 
The  hollow  stem  is  found 
in  many  plants,  and  is  the 
outcome  of  economy  of  ma- 
terials in  stem  construction. 

203.  Most  Potent  Environ- 
mental Factors.  —  Instances 
showing  adaptations  to 
special  conditions  might  be 
cited  at  great  length,  but 
the  few  cases  already  given 
suffice  to  show  the  power 
of  plants  to  meet  such  con- 
ditions. It  has  already 
been  suggested  that  of  all 
the  factors  to  which  plants 
must  accommodate  them- 
selves, the  water  supply  is 
the  most  potent  in  molding 
their  form  and  visible  con- 
stitution. Indeed,  so  great 
has  this  influence  been  that 
those  plants  which  have  to  guard  against  loss  of  water  by 
transpiration  are  very  different  in  appearance  from  those 
which  find  plenty  of  water  at  their  disposal  and  may  tran- 
spire it  unstintingly  without  danger  to  themselves.  The  for- 
mer class  of  plants  are  termed  xerophytes,  or  if  growing  in  a 
salty  substratum  they  are  termed  halophytes  (see  paragraph 
208^,  while  plants  of  the  latter  class  are  called  hydrophytes. 


FIG.  167. 

A,  longitudinal  section  through  a  portion 
of  a  young  stem  of  Cecropia  adenopus, 
showing  partitions  cut  through  by  ants ; 
B,  apex  of  a  young  stem  of  Cecropia, 
showing  at  a  a  thin  place  through  which 
the  ants  cut  a  way  to  the  hollow  inte- 
rior. About  one-half  natural  size.  After 

SCHIMPER. 


320 


Introduction  to   Botany. 


FIG.  168. 

Food  bodies  of  Cecropia 
adenopus,  somewhat 
magnified.  After 

SCHIMPER. 


Plants  which  grow  under  ordinary 
conditions  of  moderately  moist  soil 
and  average  humidity  of  atmosphere, 
and  are  not  subjected  to  prolonged 
drought  during  the  growing  season, 
are  termed  mesophytes.  These  have 
less  pronounced  characteristics  of  the 
hydrophytes.  Most  of  the  mesophytes 
cast  off  their  leaves  at  the  close  of  the 
growing  season,  and  many  of  them 
die  back  to  the  ground  and  survive 
as  bulbs,  tubers,  etc.  Such  meso- 
phytes are  also  termed  tropophytes. 

204.  Xerophytic   Conditions.  —  The   following   physical 
conditions  give  rise  to  xerophytes :  A  dry  soil,  such  as  is 
found  in  desert  regions ;  a  low  temperature  of  the  soil,  the 
roots  being  able  to  abstract  but  little  water,  even  when 
plenty  is  present,  from  soils  whose  temperature  approaches 
zero;  soils,  such  as  those  of  peat  bogs,  abounding  in  humic 
acids,  these  acids  in  some  way  diminishing  the  absorptive 
power  of  roots. 

205.  Halophytic  Conditions.  —  The  halophytes  have  been 
evolved  in  soils  whose  water  contains  more  than  0.5^  of 
salts  in  solution,  as  is  the  case  along  seacoasts,  in  salt 
marshes,  and  in  the  dry  beds  of  ancient  salt  waters.    A  low 
relative  humidity,  a  high  temperature,  and  a  low  pressure 
of  the  atmosphere  all  hasten  transpiration,  and  assist  in 
the  evolution  of  xerophytic  and  halophytic  characters. 

206.  Hydrophytic  Conditions.  —  The  hydrophytes  have 
been  produced  under  conditions  opposite  to  those  above 
enumerated ;  namely,  in  soils  abundantly  provided  with 
water  even  to  saturation  and  submergence,  of  sufficiently 
high  temperature  to  enable  the  roots  to  absorb  the  water 


FIG.  169. 

North  American  Xerophytes.  In  the  foreground  Cereus  ingens  (dome-shaped).; 
to  the  right  of  this  Agave ;  back  of  these  an  arboreus  Yucca ;  in  the  background 
to  the  right,  Cereus  gig anteus. 


322  Introduction  to  Botany. 

readily,  and  containing  but  a  moderate  amount  of  soluble 
salts. 

207.  Character  of  Xerophytes.  —  Since  the  xerophytes 
have  developed  under  conditions  requiring  a  reduction  of 
transpiration  and  the  appropriation  of  as  much  as  possible 
of  the  scant  water  supply,  we  find  that  they  are  character- 
ized by  (i)  a  reduction  of  leaf  and  stem  surfaces  without  a 
corresponding  reduction  in  volume, — that  is,  while  the  stems 
and  leaves  are  less  branched  and  expanded,  they  are  more 


FIG.  170. 

Zygophyllum  cornutum  from  the  Algerian  desert.    After  ENGLER. 

fleshy,  as  in  Cactus,  Portulacca,  and  Mesembryanthemum 
(Fig.  169);  (2)  a  reduction  of  intercellular  spaces  so  that 
more  room  may  be  obtained  for  the  storage  of  water, 
the  transpiring  surfaces  being  reduced  at  the  same  time ; 
(3)  increase  in  tissues  which  absorb,  conduct,  and  store 
water;  (4)  frequently  a  covering  of  hairs,  scales,  etc., 
which  reduce  transpiration ;  (5)  a  lengthening  of  the  pali- 
sade cells ;  (6)  depression  of  the  stomata  beneath  the  sur- 
face, and  (7)  the  production  of  mucilage  which  assists  in 
retaining  the  water  within  the  plant. 


Adaptation  to  Environment. 


323 


208.    Character  of  Halophytes. 

—  The  halophytes  have  essen- 
tially the  same  character  as  the 
xerophytes  ;  for  although  they 
grow  in  soils  abundantly  sup- 
plied with  water,  their,  roots  ab- 
sorb it  with  great  difficulty. 

Whatever  be  the  cause  of  the 
difficulty  to  plants  in  obtaining 
water,  the  methods  of  adaptation 
to  the  unfavorable  conditions  for 
absorbing  water  are  essentially 
the  same,  as  will  be  seen  by  com- 
paring Zygophyllum  cornutum 
(Fig.  170),  a  plant  from  the  Al- 
gerian desert,  Batis  maritima 
(Fig.  i/i),  growing  on  wet,  salt, 
tropical  beaches,  and  Cassiope  te- 

tragona  (Fig. 

172),  growing 

in  the  cold  soil 

of  Greenland. 

In     each     of 

these     plants 

the  reduction  of  the  transpiring  surface 

is  very  marked. 

209.   Character  of  Hydrophytes.  —  The 

hydrophytes  are  abundantly  supplied  with 

water  and  do  not  need  to  provide  special 

devices  to  guard  against  its  loss.     But 


FIG.  171. 

Batis  maritima.  Halophyte  from  a 
tropical  sea  beach.  After  DAM- 
MAR. 


Cassiope   tetragona, 

bearing  small,  leath-   because  they  are  often  in  part,  or  wholly, 


After  WARMING. 


Submerged  in    water    theY    are   in   danger 

of  suffering  from  lack  of  sufficient  oxygen 


Introduction  to  Botany. 


or  carbon  dioxide.  Therefore  we  find  them  modified  in 
such  a  way  as  to  facilitate  the  entrance,  circulation,  and 
storage  of  gases;  and  to  this  end  the  surfaces  of  leaves  and 
stems  are  increased,  and  in  the  parts  which  are  not  sub- 
merged stomata  are  abundantly  provided. 

The  yellow  water  lily,  Nelumbo  lutea,  serves  as  a  good 
example  of  hydrophytes  which  are  partly  submerged  (Figs. 


FIG.  173. 
Nelumbo  lutea  growing  in  a  lake. 

69  and  173).  Its  underground  stems  grow  horizontally  a 
few  inches  below  the  surface  of  the  mud,  in  relatively 
shallow  and  still  water.  Leaf  and  flower  stems  grow  verti- 
cally from  the  horizontal  stems.  The  round,  peltate  leaves 
which  are  first  produced  float  on  the  surface  of  the  water, 
while  most  of  the  later  leaves  rise  for  some  distance  above 
it,  so  that  the  light  can  pass  under  and  strike  those  which 
are  floating.  The  stomata  are  very  numerous  on  the  upper 
side  of  the  leaf,  but  are  found  very  rarely  on  the  under 


Adaptation  to  Environment. 


side  where  they  would  become  stopped  up  by  the  water, 
even  in  the  case  of  the  taller  leaves  in  the  time  of  high 
water.  The  upper  surface  of  the  leaf  is  coated  with  wax, 
so  that  the  water  which 
falls  upon  it  rolls  off  with- 
out wetting  it  and  stop- 
ping up  the  ways  through 
the  stomata.  The  inter- 
cellular spaces  in  the  leaf 
are  large  and  numerous 
and  communicate  with 
tubular  spaces  in  the  ribs 
of  the  leaf  which  are  con- 
tinuous with  still  larger 
spaces  in  the  petioles, 
horizontal  stems,  roots, 
and  tubers.  The  sub- 
merged parts  are  thus  in 
free  communication  with 
the  atmosphere. 

If  we  examine  roots 
which  have  been  carefully 
dug  up,  we  find  that  they 
extend  but  a  short  dis- 
tance beneath  the  mud; 
indeed,  the  water-conduct- 
ing and  absorbing  ele- 
ments throughout  the 
whole  plant  are  very 
small  compared  with  those  found  in  xerophytes  or  even  in 
mesophytes. 

Thus  we  see  that  where  water  can  be  had  without  stint, 
no  special  provision  is  made  for  its  absorption,  conduction, 


FIG.  174. 

Ranunculus  flu itans.  The  lower  figure  shows 
the  land  form  and  the  upper  figure  the  water 
form,  %  natural  size.  After  SCHIMPER. 


326 


Introduction  to   Botany. 


or  conservation.  Plants  in  such  situations  can  afford  to  be 
indifferent  to  water  in  their  form  and  construction,  but 
their  attitude  toward  the  atmosphere  must  be  quite  differ- 
ent, for  they  are  in  danger  of  being  cut  off  from  it  by  the 
water,  and  of  dying  from  suspended  respiration. 

Plants  which  are  entirely  submerged 
and  floating  in  the  water  must  absorb 
all  needed  substances  from  it.  It  is, 
therefore,  necessary  for  them  to  in- 
crease the  surfaces  of  their  leaves  and 
stems  by  dividing  them  into  thin  rods 
or  plates,  and  to  have  no  tissues  very 
remote  from  the  absorbing  surfaces. 
For  plants  built  after  this  plan,  with 
no  parts  extending  into  the  air,  sto- 
mata  and  intercellular  spaces  lose  their 
importance,  and  are  lacking  or  much 
reduced  in  number  and  extent. 

The  one  most  general  characteris- 
tic of  the  hydrophytes  is  their  large 
amount  of  free  surface  in  proportion 
to  their  volume.  In  this  respect  they 
are  in  striking  contrast  to  the  xero- 
phytes,  which  frequently  have  no  more 
much  free  surface  for  a  given  volume  as  the 


FIG.  175. 

Cabomba  Caroliniana.  The 
lower  dissected  leaves 
grow  submerged  in  the 
water,  while  the  upper 
entire  leaves  extend 
above  the  surface.  After 
BELZUNG. 


than  3^  as 
hydrophytes. 

210.  Origin  of  Xerophytes,  Halophytes,  and  Hydro- 
phytes. —  The  xerophytes,  halophytes,  and  those  hydro- 
phytes which  belong  to  the  Phanerogams,  ferns,  and 
mosses,  have  probably  descended  from  mesophytes  which 
have  been  able  to  vary  sufficiently  to  adapt  themselves  to 
permanent  extremes  of  moisture  and  dryness ;  and  so, 
migrating  into  habitats  of  one  extreme  or  the  other,  they 


Adaptation  to  Environment. 


have  been  able  to  thrive  away  from  the  sharp  competition 
which  prevails  among  plants  in  more  favorable  situations. 

It  is  not  surprising  to  find  that  plants  which  have  shown 
such  great  adaptability  to  environment  as  have  the  xero- 
phytes  and  the 
hydrophytes,  are 
able  to  undergo 
radical  modifica- 
tions in  form  and 
structure  even  in 
the  lifetime  of  a 
single  individual, 

B 
FIG.  176. 


Cross  section  of  stems  of  Callitriche  stagnalis.  A, 
from  a  plant  growing  in  water ;  B,  from  a  plant  grow- 
ing on  land.  Note  how  much  smaller  are  the  inter- 
cellular spaces  and  how  much  thicker  the  epidermis 
in  the  latter  form.  X  60.  After  SCHENCK. 


if  the  conditions 
under  which  they 
are  growing  be- 
come much  al- 
tered. Ranuncu- 
lus fltiitans,  for 
instance,  which  has  its  leaves  divided  into  fine  filamentous 
segments  when  growing  in  the  water,  produces  leaves  with 
much  broader  divisions  when  growing  on  the  land  (Fig.  174). 
So,  too,  the  submerged  leaves  of  Cabomba  Caroliniana  are 
finely  divided,  while  the  floating  leaves  are  entire  (Fig.  175). 

The  stems  of  Callitriche  stagnalis  when  growing  in  the 
water  have  intercellular  spaces  occupying  about  half  of 
their  volume,  while  the  intercellular  spaces  of  stems  of  the 
same  species  found  growing  on  the  land  are  relatively 
quite  small  (Fig.  176). 

Having  become  aware  of  the  ability  of  plants  to  undergo 
adaptive  changes,  we  are  prepared  to  understand  in  our 
study  of  the  plants  of  different  regions,  and  of  past  ages, 
how  plants  haVe  been  able  to  migrate  from  one  latitude  to 
another  without  suffering  extinction. 


CHAPTER  XV. 
PLANTS  OF  DIFFERENT  REGIONS. 

211.  Original  Distribution  of  Plants.  —  Plants  occur  in 
some  form,  either  on  the  land  or  in  the  water,  from  the 
equator  to  the  poles.     Where  they  first  originated  on  the 
earth,  or  whether  independently  in  more  than  one  locality, 
is  not  known.     It  is  known,  however,  that  when  they  had 
advanced  sufficiently  in  the  course  of   their  evolution  to 
form  tissues  which  could  be  preserved  as  fossils,  they  were 
fairly  uniformly  distributed  throughout  all  latitudes,  the 
earth  down  to  Middle  Tertiary  time  having  a  temperate  cli- 
mate, even  within  the  arctic  circle.     After  that  time,  snow 
and  ice  accumulated  in  and  beyond  the  arctic  circle,  and 
extended  far  southward  in  the  form  of   moving  glaciers. 
Land  plants  had  then  to  move  southward  by  means  of 
their  seeds  and  spores,  or  become  exterminated.      When 
the  ice  again  retreated  toward  the  poles,  only  those  exiled 
plants  which  were  able  to  adapt  themselves  to  extremes  of 
temperatures  moved  northward.     We  accordingly  find  that 
the  floras  of  the  tropical,  temperate,  and  frigid  zones  are 
dominated  by  different  kinds  of  plants. 

212.  Factors  governing  Floras.  —  Within  each  zone  there 
are  factors,  other  than  temperature,  which  sort  the  vege- 
tation into  groups   of  various  characters.     These  factors 
are  water  supply,  relative  humidity  of   the  atmosphere, 
winds,  and  nature  of  the  soil. 

328 


Plants  of  Different  Regions.  329 

Whether  the  vegetation  of  a  region  shall  consist  largely 
of  trees  and  shrubs,  or  of  grasses  and  low  herbs,  depends 
for  the  most  part  upon  the  depth  and  amount  of  the  soil 
water.  Trees  will  predominate  in  regions  where  the  vege- 
tative period  is  warm,  the  atmosphere  humid  and  compara- 
tively quiet,  particularly  in  winter,  and  where  there  is  an 
unfailing  subterranean  water  supply.  It  is  unessential  to 
trees  when,  and  with  what  frequency,  rains  occur,  provided 
they  are  of  sufficient  amount  during  the  year  to  replenish 
the  soil  reservoirs. 


FIG.  177. 
Drawing  from  a  photograph  of  a  neglected  tree  claim  in  western  Kansas. 

Since  the  roots  of  trees  go  deep,  they  can  avail  them- 
selves of  water  supplies  which  are  beyond  the  reach  of 
grasses  and  other  plants  with  shallow  roots.  The  fact  that 
the  roots  of  trees  extend  to  considerable  depths  enables 
them  to  become  established  along  the  banks  of  streams  in 
regions  where  the  annual  rainfall  is  too  scant  to  penetrate 
beyond  the  superficial  layers  of  the  soil.  The  water  from 
streams  percolates  some  distance  beyond  their  beds,  so  that 
fringes  of  timber  may  follow  water  courses  for  hundreds 
of  miles  through  prairie  or  even  desert  regions. 

Trees  may  be  made  to  grow  where  they  would  not 
naturally,  by  keeping  the  surface  soil  loose  and  mellow 
with  the  plow,  so  that  rains  may  percolate  to  some  depth 


330  Introduction  to  Botany. 

and  that  the  water  thus  caught  may  be  retained  by  the 
mulch  of  loose  soil  at  the  surface.  The  success  of  tree 
claims  in  the  semi-arid  regions  of  the  United  States  de- 
pended largely  upon  the  degree  of  persistence  in  this 
mode  of  treatment.  Figure  177  is  a  drawing  from  a  pho- 
tograph of  a  claim  which  was  planted  with  trees  and  neg- 
lected, while  Figure  178  shows  the  result  of  cultivation  in 
the  neighborhood  of  the  neglected  claim. 

In  regions  where  the  rains  occur  frequently  during  the 
growing  season,  though  not  in  sufficient  amount  to  produce 


FIG.  178. 

Drawing  from  a  photograph  of  a  tree  claim  in  western  Kansas  that  has  been 
properly  cultivated. 

a  perennial  water  supply  in  the  deeper  strata  of  the  soil, 
grasses  predominate,  while  trees,  with  the  exception  of  those 
of  xerophilous  character,  such  as  occur  in  savannas,  are 
absent.  The  dry  atmosphere  and  strong  winds  which  are 
apt  to  occur  in  treeless  regions  are  much  less  inimical  to 
grasses  than  to  trees,  because  the  former  keep  close  to  the 
ground,  where  the  adverse  conditions  are  less  pronounced. 
The  character  of  the  soil  may  also  impress  its  stamp  upon 
the  flora  of  a  region.  Thus,  to  take  examples  from  a  single 
genus,  CEnothera  laciniata  occurs  in  dry  sandy  soils,  (Eno- 
thera  rhombipetala  is  a  prairie  plant,  and  CEnothera  Mis- 


Plants  of  Different  Regions.  331 

souriensis  abounds  along  the  crests  of  limestone  hills. 
Grasses,  and  other  plants  with  creeping  underground 
stems,  are  well  adapted  to  take  possession  of  the  shifting 
soil  of  sand  dunes  where  competition  with  other  plants 
less  suited  to  such  situations  is  not  sharp,  and  in  this  indi- 
rect way  the  unstable  sandy  soil  gives  a  distinct  character 
to  its  vegetation. 

If  all  plants  were  able  to  accommodate  themselves 
equally  well  to  different  kinds  of  climate  and  soils,  we 
might  expect  to  find  them  uniformly  distributed,  except- 
ing where  broad  waters  intercept  their  migration ;  but 
they  show  great  diversity  in  their  adaptability  to  different 
external  factors,  most  of  them  being  unable  to  traverse 
deserts  or  lofty  mountains.  Some  are  unable  to  maintain 
themselves  where  the  annual  precipitation  falls  below  a 
certain  amount,  where  the  ranges  of  temperature  pass  cer- 
tain maximum  and  minimum  limits,  or  where  the  prevailing 
winds  exceed  a  certain  velocity.  It  is  because  of  its  bear- 
ing on  this  diverse  capacity  that  the  subject  of  plant  dis- 
tribution is  one  of  high  importance  in  the  study  of  plant  life. 

213.  Vegetation  in  the  Tropics.  —  In  the  tropics  the  tem- 
perature is  uniformly  high,  excepting  in  the  mountains, 
averaging  from  20°  to  28°  C.  (68°  to  82.4°  F.)  throughout 
the  year.  In  general  the  tropics  are  regions  of  high 
annual  rainfall  (see  rainfall  map,  Fig.  179),  the  precipita- 
tion along  the  coast  and  in  the  mountains  amounting  in 
some  localities  to  4  or  5  meters.  The  greater  part  of  Cen- 
tral and  South  America  has  an  annual  rainfall  of  130  to 
200  centimeters,  and  for  the  most  part  of  the  East  Indian 
Archipelago,  and  of  the  east  coast  of  tropical  Asia,  the 
annual  precipitation  exceeeds  200  centimeters.  In  tropical 
Africa  there  is  a  zone  10°  broad  where  the  rainfall  amounts 
to  1 30  to  200  centimeters. 


Introduction  to  Botany. 


RAINFALL 


FIG. 


Rainfall  Map  of  the  World.     After  data 


Plants  of  Different  Regions. 


333 


179. 


in  SCHIMPER'S  Pflanzengeographie. 


334  Introduction  to  Botany. 

For  the  greater  part  of  the  tropics  there  is  a  wet  and  a 
dry  season,  the  wet  season  occurring  in  summer ;  but  the 
dry  season  in  many  places  is  not  without  rains. 

On  account  of  the  uniformly  high  temperature  and 
abundance  of  moisture,  plants  make  a  phenomenal  growth 
in  the  tropics.  It  is  recorded,  for  instance,  that  a  shoot  of 
Bambusa  grew  nearly  8  meters  within  a  single  month,  and 
that  a  Dendrocalamtis  (Fig.  1 80)  increased  in  length  on  the 
average  7.7  millimeters  during  the  daytime  and  13  milli- 
meters during  the  nighttime  of  each  day. 

On  account  of  the  moist  atmosphere  many  kinds  of  epi- 
phytes flourish  in  the  tropical  forests,  sometimes  growing 
so  luxuriantly  as  to  break  off  the  branches  of  trees  with 
their  weight  (Fig.  16).  Besides  the  epiphytes,  the  plants 
which  characterize  the  vegetation  of  the  tropics  are  the 
palms,  bamboos,  many  species  of  climbing  plants,  and  tree 
ferns.  The  luxuriant  character  of  a  tropical  forest  is  well 
shown  by  Fig.  181. 

In  regions  where  the  dry  season  is  well  pronounced,  trees 
shed  their  leaves  at  that  time  just  as  they  do  in  the  tem- 
perate zones  in  winter,  but  where  the  rainfall  occurs 
throughout  the  year,  and  everywhere  along  water  courses, 
the  leaves  are  not  as  a  rule  all  cast  off  at  once,  but  are 
shed  gradually  and  from  different  branches  at  different 
times.  At  any  season  in  such  regions  trees  may  be  seen 
with  leaves,  flowers,  and  fruits  in  various  stages  of  devel- 
opment. 

The  damp  atmosphere  of  the  forests  in  regions  where 
rainfall  is  frequent  throughout  the  year  does  away  with 
the  necessity  of  thick  layers  of  cork  as  a  protective 
covering  for  the  bark,  and  the  trunks  of  trees  are,  in  con- 
sequence, relatively  smooth  and  frequently  green  in  color. 
To  the  thinness  of  the  bark  is  probably  due  the  peculiar 


Plants  of  Different  Regions.  335 


gj 


|! 


6 

a 


336 


Introduction  to  Botany. 


Plants  of  Different  Regions.  337 


FIG.  182. 

Parmentiera  cefeifera,  bearing  fruit  on  the  trunk  and  old  branches:    Ceylon. 
After  SCHIMPER'S  Pflanzengeographie. 


338 


Introduction  to  Botany. 


phenomenon  of  flowers  and  fruits  borne  on  the  old 
branches  and  even  on  the  trunks  of  trees,  as  shown  in 
Fig.  182. 

In  the  moist  forests  the  buds  of  trees  do  not  prepare  for 
their  period  of  rest  by  the  production  of  elaborate  scales, 

such  as  are  found  in  the  winter 
buds  of  trees  of  temperate  re- 
gions, and  the  resumption  of 
growth  of  resting  buds  does 
not  differ  essentially  from  the 
uninterrupted  apical  elongation 
of  shoots  at  the  height  of  the 
growing  season  (Fig.  183). 

214.  Vegetation  in  Temperate 
Regions.  —  The  temperate  re- 
gions are  characterized  by  much 
greater  extremes  of  temperature 
than  occur  in  the  tropics,  the 
minimum  for  the  winter  months 
running  in  some  places  far  below 
the  freezing  point,  and  the  maxi- 
mum in  summer  rising  as  high  as 
50°  C.  (122°  Fahr.).  Those  por- 
tions of  the  temperate  zones 
which  lie  next  the  tropics  gradu- 
ally blend  with  the  latter  in  their 
physical  characteristics  and  veg- 
etation. The  amount  of  precipitation  is  much  less  in  the 
temperate  zones  than  in  the  tropics,  the  greater  part  of 
Central  Asia  and  large  parts  of  Europe  and  western  North 
America  having  an  annual  rainfall  of  20  to  60  centimeters, 
while  the  deserts  of  North  America  and  the  greater  part 
of  the  Sahara  and  of  the  great  deserts  of  Asia,  where  the 


FIG.  183. 

K,  young  shoot,  with  apical  bud, 
of  Tabernaemontana  dichotama; 
L,  young  shoot  of  Clusiagrandi- 
flora  (?).  After  P.  GROOM. 


Plants  of  Different  Regions. 


339 


34°  Introduction  to  Botany. 

rainfall  averages  less  than  20  centimeters  yearly,  lie  within 
this  region.  A  large  part  of  western  Europe  and  of 
eastern  North  America  has  a  rainfall  of  60  to  130  cen- 
timeters, while  in  some  of  our  Southern  states,  and  in  parts 
of  Europe,  the  precipitation  ranges  between  130  and  200 
centimeters  annually. 

The  low  winter  temperature  of  the  greater  part  of  the 
temperate  zones  precludes  the  presence  of  many  plants 
which  are  at  home  in  the  tropics,  but  which  have  thus  far 
been  unable  to  adapt  themselves  to  low  temperatures. 
Thus  palms,  bamboos,  bananas,  etc.,  do  not  venture  far 
outside  of  the  tropics,  but  in  their  stead  we  find  pines,  firs, 
spruces,  and  other  conifers,  and  forests  of  oaks,  hickories, 
walnuts,  and  beeches,  which  in  the  tropics  have  represen- 
tatives, as  a  rule,  only  in  the  mountains.  How  the  tropical 
and  temperate  forms  mingle  in  the  southern  part  of  the 
north  temperate  zone  is  shown  by  Fig.  184,  which  repre- 
sents dwarf  sabal  palms  and  pine  trees  occupying  the  same 
ground.  In  Florida  and  Louisiana  the  boughs  of  forest 
trees  are  often  bedecked  with  luxuriant  growths  of  Tilland- 
sia  usneoides,  an  epiphyte  which  is  also  native  to  tropical 
forests  (Fig.  185). 

The  effect  of  the  amount  of  annual  rainfall  on  the  char- 
acter of  the  vegetation  in  the  temperate  zone  may  be  seen 
as  one  passes  across  the  United  States  from  east  to  west. 
Along  the  Atlantic  and  Gulf  coasts  the  rainfall,  amounting 
to  more  than  100  centimeters  annually,  is  distributed 
throughout  the  year,  with  the  maximum  amount  in  summer. 
The  rainfall  gradually  diminishes  toward  the  west,  until  at 
the  Mississippi  River  the  annual  amount  is  about  60  centi- 
meters. Along  the  coasts,  and-  in  the  mountains  of  the 
Atlantic  states,  the  rainfall  being  sufficient  to  keep  the  soil 
moist  at  considerable  depths,  forest  trees  abound,  so  that 


Plants  of  Different  Regions.  341 

the  early  settlers  were  obliged  to  make  clearings  with  ax 
and  grub  hook  in  order  to  obtain  land  suitable  for  agri- 
culture. 

But   as  the   rainfall  diminishes   toward    the   west   and 
north,  we  find  the  forests  giving  way  to  prairies,  the  grasses 


FIG.  185. 

Tillandsia  usneoides  covering  and  pendent  from  Quercus  virens.    After  photograph 

by  WEBBER. 

and  herbaceous  plants  which  characterize  them  being  able 
to  obtain  sufficient  moisture  from  the  summer  rains  to 
flourish  where  trees,  with  their  larger  demands  on  moisture, 
are  unable  to  subsist,  excepting  along  water  courses.  West- 
ward from  the  Mississippi  to  the  Rocky  Mountains  the  rain- 
fall, which  occurs  for  the  most  part  in  the  spring,  early 
summer,  and  fall,  steadily  diminishes,  and  the  grasses  and 


342  Introduction  to   Botany. 

herbs,  and  the  trees  following  the  streams,  are  represented 
for  the  most  part  by  forms  specially  adapted  to  withstand 
dry  weather. 

Beyond  the  Rocky  Mountains,  to  the  Sierra  Nevadas, 
there  is  a  high  plateau  where  the  rainfall  is  about  30  centi- 
meters and  less,  and  here  we  find  xerophytes  of  a  more 
pronounced  type,  such  as  cacti,  Agaves,  and  sage  brush. 
Across  the  mountains,  on  the  Pacific  slope,  the  rainfall  in- 
creases, amounting  to  about  93  centimeters  in  the  north 
Pacific  states,  and  to  45  centimeters  in  the  northern  and 
central  parts  of  California,  where,  however,  the  rainfall 
occurs  in  winter  and  so  occasions  a  peculiar  form  of  vege- 
tation especially  adapted  to  these  conditions.  The  shrubs 
and  trees  have  leaves  which  are  commonly  leathery  and 
often  entire,  and  so  adapted  to  reduce  transpiration  and 
perform  their  food-building  function  through  the  dry  sum- 
mer season. 

215.  Light   in   Temperate   Regions. — The  intensity   of 
light  diminishes  from  the  equator  to  the  poles;  but  since 
the  length  of  the  day  in  summer  is  greater  in  the  temperate 
than  in  the  equatorial  regions,  the  total  amount  of  illumina- 
tion in  the  twenty-four  hours  of  a  summer's  day  may  be 
greater  in  the  temperate  regions.     In  latitude  30°  on  the 
longest  summer  day  the  sun  is  above  the  horizon  13  hours 
and  56  minutes;  in  latitude  50°,  16  hours  and  9  minutes; 
in  latitude  60°,  18  hours  and  30  minutes;  and  in  latitude 
66J°,  24  hours.     Accordingly,  in  passing  from  the  equator 
to  the  poles,  the  diminishing  energy  of  the  sun  which  comes 
to  plants  in  a  given  period  is,  in  part,  compensated  by  the 
increasing  length  of  time  in  which  the  energy  is  available 
each  day. 

216.  Vegetation  in  Arctic  Regions. — The  arctic  region 
is  characterized  by  its  low  average  temperature,  its  long 


Plants  of  Different  Regions.  343 

winter  night  and  long  summer  day,  and  its  cold,  dry  winds. 
During  the  winter  night,  the  land  is  shrouded  in  ice  and 
snow  which  is  frequently  not  sufficiently  melted  for  vege- 
tation to  appear  before  about  the  first  of  July.  July,  which 
has  an  average  temperature  varying  in  different  localities 
from  3.8°  C.  to  8.8°  C.  (38.8°  to  47.8°  F.),  and  even  rising 
as  high  as  13.4°  C.  (56.1°  F.)  at  Ustjansk,  is  the  warmest 
month.  The  sun  is  entirely  above  the  horizon  for  65  days 
in  latitude  70°,  and  for  134  days  in  latitude  80°,  and,  during 
part  of  these  periods,  the  sum  of  the  sun's  energy  avail- 
able to  plants  for  each  twenty-four  hours  may  be  even 
greater  than  the  available  amount  at  the  equator  at  the 
same  time.  Because  of  the  cold,  the  shortness  of  the 
vegetative  period,  and  the  dry  winters,  trees  are  able  to 
make  only  a  feeble  growth,  and  they  do  not  exist  far 
beyond  the  arctic  circle. 

About  the  first  of  July,  when  the  snow  and  ice  have 
melted  in  places,  and  sufficient  heat  has  accumulated  in 
the  soil,  vegetation  in  general  suddenly  starts  into  new 
growth.  Kjellman,  the  botanist  of  the  Vega  Expedition, 
says  of  the  beginning  of  the  vegetative  period  within  the 
arctic  circle :  "  It  is  here  not  the  same  as  in  the  more 
southern  latitudes,  where  one  species  after  another  grad- 
ually comes  to  maturity.  In  the  high  north  there  are  no 
spring,  summer,  and  autumn  floras  composed  of  various 
plants  blooming  at  different  times,  as  farther  to  the  south ; 
in  the  polar  regions  everything,  or  nearly  everything, 
springs  into  life  at  once ;  development  begins  everywhere 
at  the  same  stage  and  proceeds  with  equal  rapidity,  so  that 
all  flowering  plants  are  suddenly  and  at  the  very  beginning 
of  the  vegetative  period  decked  in  their  summer  attire." 

The  vegetative  period  lasts  only  till  the  end  of  August, 
there  being  but  two  months  of  each  year  during  which 


344 


Introduction  to  Botany. 


plants  can  accumulate  food  and  produce  seeds.  Kjellman 
says  of  the  close  of  the  growing  season  :  "  An  arctic  land- 
scape at  the  advent  of  winter  is  most  nearly  like  a  southern 
region  which  has  been  desolated  by  a  heavy  frost  before 
its  season.  Many  plants  are  interrupted  at  the  height  of 
their  growth  and  stand  with  frozen 
lifeless  leaves,  with  swelling  flower 
buds,  with  half-open  or  entirely  open 
flowers,  and  with  half  or  entirely 
ripened  fruit.  No  preparation  has 
been  made  for  the  winter  rest;  while 
plants  are  in  full  activity,  they  are 
paralyzed  by  the  stiffening  cold." 
But  how  well  the  plants  of  this 
region  are  able  to  withstand  a  catas- 
trophe that  would  prove  fatal  to 
those  of  lower  latitudes  has  already 
been  recounted  on  page  311. 
It  might  be  expected  that  the  plants  of  arctic  regions 
would  prepare  for  winter  by  ripening  the  new  branches 
and  producing  protective  scales  for  the  young  buds ;  but 
yet  it  seems  clear  that  making  the  protoplasts,  in  and  of 
themselves,  resistant  to  the  severe  cold  is  the  better  plan, 
for  the  short  vegetative  period  necessitates  the  rushing 
forward  of  the  processes  of  vegetation  and  reproduction, 
and  affords  no  time  for  special  defensive  preparations. 

As  would  be  expected,  growth  is  very  slow  in  the  polar 
regions;  measurements  made  on  the  willow,  Salix polaris 
(Fig.  1 86),  showed  that  in  most  instances,  by  the  end  of 
the  growing  season,  shoots  had  increased  from  i  to  5 
millimeters  in  length,  and  at  most  from  5  to  1 1  milli- 
meters. A  forest  tree  which  was  83  millimeters  thick 
at  the  base  was  found  to  have  544  rings  of  annual 


FIG.  186. 


Salix  polaris.     Natural  size. 
After  SCHIMPER. 


Plants  of  Different  Regions. 


345 


FIG.  187. 

Zilla  spinosa,  slightly  reduced.    From  the  Sa- 
hara desert.    After  PRANTL. 


growth,   the   rings   having   an   average    breadth   of  0.15 
millimeter. 

The  polar  regions 
possess  no  families  of 
plants  peculiar  to  them- 
selves, the  plants  which 
appear  there  being 
dwarfed  and  xerophytic 
representatives  of  fami- 
lies which  dominate  the 
north  temperate  zone. 

217.  Vegetation  of 
Desert  Regions.  —  The 
deserts  occupy  a  consid- 
erable area  of  the  earth. 
In  north  Africa  the  Sa- 
hara desert  alone  nearly 
equals  the  United  States  in  size,  and  its  area  is  more  than 

doubled  by  the  deserts  of  Ara- 
bia and  of  south  and  central 
Asia.  To  this  must  be  added  a 
large  tract  between  .the  Sierra 
Nevada  and  Rocky  Moun- 
tains, a  narrow  strip  east  of 
the  Rocky  Mountains,  a  large 
portion  of  central  and  south- 
western Australia,  and  a  nar- 
row strip  along  the  western 
border  and  in  the  south  cen- 
tral part  of  South  America. 
The  total  area  of  these  desert 
regions  equals  approximately 
the  area  of  the  North  Ameri- 


FlG.  188. 


Alhagi  maurorum.    From  the  Sahara. 
After  TAUBERT. 


346 


Introduction  to  Botany. 


can  continent.  They  have  a  rainfall  of  less  than  30  centi- 
meters annually,  and,  for  the  most  part,  are  habitable  only 
to  xerophytes ;  and  even  these  plants,  which  are  constructed 
specially  to  defy  drought,  occur  as  more  or  less  isolated 
individuals. 

For  most  of  this  vast  desert  region,  the  sole  cause  of 

the  scant  vegeta- 
tion is  lack  of 
water,  the  soil  be- 
ing rich  enough  to 
support  a  luxuriant 
plant  population. 
Schimper  says  of 
the  Sahara  desert 
near  Biskra:  "The 
firm  and  mostly 
clayey  soil  between 
the  oases  presented 
the  appearance  of 
a  very  scantily 
planted  and  pecul- 
iar garden  where 
the  individual 
plants  were  sepa- 
rated by  barren 
spaces  a  meter  or 
more  in  breadth.  Most  of  the  plants  were  small,  rounded, 
dense  shrubs  which  appeared  at  first  sight  so  nearly  alike 
that  it  was  a  surprise  to  find  on  closer  examination  that 
they  possessed  different  kinds  of  leaves  or  flowers."  (Fig- 
ures 187,  1 88,  and  189  represent  plants  of  this  character.) 
In  the  same  region  occurred  a  plant  of  quite  different  char- 
acter belonging  to  the  gourd  family,  whose  thick  succulent 


FIG.  189. 

Sarcobatus  Baileyi.     From  western  North  America 
a  desert  plant.    After  COVILLE. 


Plants  of  Different  Regions.  347 

stems  bore  large  leaves  which  remained  green  throughout 
the  summer.  It  seemed  to  possess  no  special  provision  to 
prevent  transpiration,  for  the  leaves  on  severed  branches 
soon  withered.  It  was  able  to  survive  and  remain  green 
and  turgid  because  of  its  extraordinarily  long  roots,  which 
absorbed  moisture  at  great  depths. 

The  deserts  of  our  own  country  are  characterized  by 
Yuccas,  thick-leaved  Agaves,  and  cacti,  whose  succulent 
green  stems  assume  various  forms  from  oval  and  globose 
to  columnar,  the  latter  forms  sometimes  rising  to  the  height 
of  trees  (Fig.  169).  In  the  cacti,  the  leaves  are  reduced 
to  protective  spines,  and  the  chloroplasts  are  borne  in  the 
superficial  cells  of  the  cortex  of  the  stems,  while  the  major 
part  of  the  tissues  of  the  stem  serves  as  a  storehouse  for 
water. 

218.  Vegetation  of  Mountain  Heights. — The  physical 
conditions  vary  materially  from  the  base  to  the  summit  of 
high  mountains.  As  a  rule,  the  amount  of  precipitation 
increases  up  to  a  certain  height,  the  atmospheric  pressure 
diminishes  as  altitude  increases,  and  the  amount  of  heat 
energy  absorbed  by  the  atmosphere  also  diminishes ;  the 
intensity  of  illumination,  however,  increases  with  the  alti- 
tude. It  follows  from  these  conditions  that  objects  exposed 
to  the  direct  rays  of  the  sun  warm  up  quickly,  but  on  the 
withdrawal  of  sunlight  they  also  quickly  radiate  their  heat 
into  space. 

The  amount  of  transpiration  from  plants  increases  with 
the  elevation  because  of  the  increased  illumination  and 
decreased  atmospheric  pressure,  together  with  the  increased 
force  of  the  wind  at  successively  greater  heights.  At  the 
same  time  the  amount  of  absorption  by  the  roots  is  apt  to 
be  lessened  by  the  relatively  low  average  temperature  of 
the  soil. 


348 


Introduction  to  Botany. 


FIG.  190. 

Trees  at  different  elevations  on  a  mountain  side.  The  largest  trees  occur  near  the 
base  of  the  mountain.  The  dark  zone  near  the  summit  of  the  middle  range  is 
a  belt  of  trees,  the  upper  border  of  which  is  the  timber  line,  no  trees  growing 
beyond  this.  Above  the  timber  belt  is  Long's  Peak  with  its  perpetual  snow. 


Plants  of  Different  Regions.  349 

Up  to  a  certain  height  the  vegetation  may  be  more 
hygrophilous  than  in  the  lowlands,  on  account  of  increased 
rainfall;  but  higher  up  the  factors  which  accelerate  tran- 
spiration and  lessen  the  rate  of  absorption  necessitate 
special  provision  for  the  reduction  of  transpiration,  and 
xerophytes  begin  to  predominate  similar  to  those  which 
characterize  desert  and  polar  regions.  Trees  are  stunted 
in  their  growth  beyond  a  certain  height,  and  finally  an 
elevation  is  reached  beyond  which  they  are  unable  to 
exist.  The  line  where  the  growth  of  trees  ceases  is 
known  as  the  timber  line  (see  Fig.  190). 

One  finds  in  ascending  mountains  in  the  tropics,  that 
the  vegetation  gradually  changes  in  its  aspect,  the  plants 
at  the  base  of  the  mountains  being  tropical,  those  farther 
up  are  warm  temperate  and  temperate  forms,  until,  at  the 
height  of  perpetual  snows,  polar  plants  appear.  Indeed, 
some  of  the  same  species  of  plants  that  occur  in  the  po- 
lar regions  may  be  found  near  the  summit  of  tropical 
mountains. 

Where  representatives  of  the  same  species  occur  at 
different  elevations,  it  is  found  that  at  successively  greater 
heights  the  internodes  become  more  and  more  shortened, 
the  leaves  smaller,  thicker,  and  tending  to  cluster  in  rosettes, 
and  the  roots  longer,  so  that  the  identity  of  the  same 
species  at  the  two  extremes  would  not  be  recognized  but 
for  the  intervening  forms  (see  Fig.  191). 

When  we  compare  the  plants  of  tropical,  temperate,  and 
frigid  zones,  and  of  desert  and  mountain  regions,  we  find 
that  their  chief  modifications  of  form  and  structure  have 
special  reference  to  the  available  water,  and  that  the  same 
general  modifications  are  found  to  serve  wherever  reduction 
of  transpiration  becomes  necessary.  The  modification  of 
the  protoplasts  of  arctic  plants,  so  that  they  are  able  to 


35°  Introduction  to  Botany. 

withstand  very  low  temperatures,   even  at  the  height  of 
their  vegetative  condition,  is  of  particular  interest,  for  it 


FIG.  191. 

Helianthemum  vulgare.    L,  the  lowland  form  ;  M,  the  mountain  form  ;  both  rather 
less  than  one-half  natural  size.    After  BONNIER. 

suggests  the  almost  limitless  possibilities  of  modification 
wherever  necessity  urges  with  penalty  of  extinction. 


CHAPTER  XVI. 
PLANTS  OF  PAST  AGES. 

219.  Antiquity  of  Plants.  —  Only  approximate  estimates 
can  be  made  of  the  length  of  time  which  has  elapsed  since 
the  waters  began  to  lay  down  the  stratified  rocks  of  the 
Cambrian  period,  whose  fossils  contain  the  earliest  evidence 
of  the  life  of  the  earth.     An  average  of  the  estimates  of 
those  best  qualified  to  judge  is  between  twenty-five  million 
and   seventy-five    million   years.      In   all   probability   life 
existed  untold  ages  before  this  time  in  very  simple  forms 
which  were  not  of  a  character  to  leave  their  impress  in  the 
rocks.     If  the  great  quantities  of  graphite  existing  in  the 
rocks  of  the  Algonquin  period  are  of  plant  origin,  as  is 
probable,  plant  life  must  at  that  early  time  have  already 
attained   an    enormous    quantitative    development    before 
much  complexity  of  structure  had  been  evolved. 

220.  Primitive  Physical  Conditions. — The  physical  con- 
ditions were  probably  such  as  to  incite  and  sustain  rapid 
growth  and  multiplication.     The  atmosphere  was  charged 
with  aqueous  vapor  and  carbon  dioxide,  a  part  of  which 
has  since  been  locked  up  in  limestone,  coal,  etc.,  and  the 
interior  heat  of  the  earth  may  have  contributed  to  maintain 
a  uniformly  high  temperature.     The  oceans    during   the 
Cambrian,  Ordovician,  and  Silurian  periods  undoubtedly 
abounded  in  Algae,  but  because  of  the  uncertainty  in  the 
preservation  of  their  tissues  as  fossils,  or  of  their  leaving 
impressions  in  the  rocks,  positive  identification  of  Algae  is 


352  Introduction  to  Botany. 

seldom  possible.  In  the  Silurian  rocks,  however,  have  been 
found  the  silicified  remains  of  a  large  plant  which  appears 
to  be  closely  related  to  the  modern  Laminarias  ;  Fuctis  also, 
described  on  page  275,  being  a  near  relative.  Dawson 
named  it  Nematopkyton^  and  wrote  of  it :  "  When  we  con- 
sider that  Nematophyton  was  a  large  tree,  sometimes  attain- 
ing a  diameter  of  two  feet  and  a  stature  of  at  least  twenty 
before  branching,  that  it  had  great  roots  and  gave  off  large 
branches,  and  that  it  was  an  aerial  plant,  probably  flourish- 
ing in  swampy  flats,  that  its  seeds  are  so  large  and  complex 
as  hardly  to  be  regarded  as  mere  spores,  we  have  evidence 
that  there  were  in  this  early  Paleozoic  period  plants  scarcely 
dreamt  of  by  modern  botany." 

221.  Devonian  Plants.  —  In  the  rocks  of  the  Devonian 
period  we  find   remains   of   representatives  of  nearly  all 
forms  of  the  higher  Cryptogams,  the  tree  ferns  (Fig.  192) 
being  of  most  frequent  occurrence.     In  the  forests  of  the 
Devonian  occurred  near  relatives  of  the  modern  Lycopods 
or  ground  pines,  and  a  genus  of  Gymnosperms,  known  as 
Cordaites,  having  leaves  about  50  centimeters  long  (Fig. 
192).      All   conditions   were   favorable   for   an   abundant 
growth  of   plant  life,  and  the  waters  must   have  teemed 
with  forms  which  have  left   no    impression  in  the  rocks. 
The  greatest  petroleum-bearing  strata  in  the  world  belong 
to  the  Silurian  and  Devonian  periods,  and  since  the  source 
of  petroleum,  natural  gas,  etc.,  is  evidently  to  be  attributed 
to  plant  'as  well  as  to  animal  remains,  the  amount  of  or- 
ganic materials  built  up  by  the  plants  of  those  periods  is 
incalculable.     (It  will  be  remembered  that  animals  obtain 
their  food  already  organized  from  plants.) 

222.  Carboniferous   Plants.  —  The  Carboniferous  period 
is  of  particular  interest  because  the  remains  of  its  vege- 
tation constitute  the  chief  part  of  the  coal  supply.     The 


Plants  of  Past  Ages. 


353 


softer  coals  still  give  clear  evidence  of  their  origin,  for  they 
appear  to  be  chiefly  the  carbonized  masses  of  the  stems 
and  leaves  of  ferns,  Lycopods,  and  Calamites  (see  Fig.  192). 
Even  those  coals  which  have  been  so  much  altered  from 
their  original  condition  that  the  naked  eye  is  unable  to 
detect  their  vegetable  origin  are  found  by  means  of  the 


FIG.  192. 

Carboniferous  Plants.  In  the  foreground  on  the  left  Lepidodendrons  and  Sigillarias 
(relatives  of  the  modern  Lycopods)  ;  just  back  of  these  Calamites,  with  branches 
in  whorls  (relatives  of  the  modern  horsetails).  On  the  right  tree  ferns;  in  the 
background,  in  addition  to  the  foregoing,  Cordaites  (low  with  upright  leaves) . 

microscope  to  contain  the  cells  and  tissues  of  plants. 
Many  of  the  ferns  of  this  period  attained  the  size  of  trees, 
and  the  Lepidodendrons  reached  a  height  of  50  to  75  feet. 
The  Lycopods,  as  many  as  eighty  species  of  which  have 
been  found,  also  grew  to  great  size.  The  Calamites,  which 
are  near  relatives  of  the  modern  horsetails,  also  attained 
great  proportions  and  apparently  occupied  the  inundated 


354  Introduction  to  Botany. 

flats  along  the  borders  of  the  forests  of  ferns,  Sigillarias, 
etc.  (see  Fig.  192). 

The  coal-bearing  areas  of  the  United  States  are  about 
300,000  square  miles  in  extent,  and  about  50,000  square 
miles  of  this  are  workable.  The  coal  seams  in  the  work- 
able fields  average  from  4  to  10  feet  in  thickness,  and  in 
some  localities  they  reach  a  maximum  thickness  of  60  to 
100  feet.  Some  idea  of  the  enormous  amount  of  vegeta- 
tion embodied  in  these  deposits  may  be  obtained  when  it  is 
remembered  that  their  thickness  is  only,  roughly  speaking, 
about  7j&  of  the  original  depth  of  the  vegetation  whkh 
formed  them.  During  this  period  there  seems  to  have 
been  a  fairly  uniform  and  temperate  climate  throughout 
North  America,  Europe,  and  Asia,  even  as  far  north  as 
Greenland,  Scandinavia,  and  Nova  Zembla. 

223.  Permian    Plants.  —  As    time    advanced    into    the 
Permian  period,  the  giant  Lepidodendrons  and  Sigillarias 
became  rare ;  the  Calamites  were  still  abundant,  and  the 
tree  ferns  even  more  so  than  in  the  Carboniferous  period. 
The    Gymnosperms    were    represented   by  the   Cordaites, 
Gingko,  and    conifers    related   to  the    modern   yews   and 
spruces.      The  ferns  dominated  the  landscape,  while  the 
Cycads  and  conifers  were  not  abundant  and  no  Angiosperms 
had  yet  appeared. 

As  the  Paleozoic  era  drew  to  its  close,  the  Lepidoden- 
drons, Sigillarias,  and  Calamites,  which  had  been  the  domi- 
nant land  vegetation,  became  almost  extinct,  the  tree  ferns 
became  less  abundant,  and  the  Cycads  and  conifers  gained 
ascendency. 

224.  Triassic  Plants.  —  In  the  Triassic  period  the  coni- 
fers were  forming  dense  forests  and  the  Cycads  (Fig.  180) 
were  common ;  the  tree  ferns  were  becoming  more  rare, 
and  only  a  few  straggling  Sigillarias  still  persisted.     The 


Plants  of  Past  Ages.  355 

smaller  forms  of  ferns  occurred  in  great  abundance,  and 
the  genus  Equisetum  appeared  with  representatives  whose 
stems  grew  to  be  four  inches  in  diameter. 

225.  Jurassic  Plants.  —  In  the  Jurassic  the  Cycads  ap- 
pear to  have  reached  their  highest  development,  occurring 
as  far  north  as  Greenland  and  Spitzbergen,  whereas  at  the 
present  time  they  are  restricted  to  the  warm  regions  of 
Mexico,  the  West  Indies,  Florida,  Africa,  and  India.     The 
conifers  of  this  period  were  more  like  those  of  the  present 
time.     There  is  some  evidence  that  Monocotyledons  had 
already  been  evolved  before  the  close  of  this  period.     The 
fact  that  ants,  bees,  wasps,  flies,  and  possibly  butterflies 
appeared  at  this  time  affords  collateral  evidence  that  the 
flowering  plants  were  already  at  hand  to  supply  food  in 
the  form  of  pollen  and  nectar. 

226.  Cretaceous  Plants. — The  beginning  of  the  Creta- 
ceous period  is  noted  for  the  apparently  sudden  appear- 
ance of  the  noble  Sequoias  of  twenty-six  species ;  and  of 
Dicotyledons,  represented  by  the  Sassafras,  poplars,  and 
Rhododendrons.    By  the  middle  of  the  Cretaceous  period  a 
characteristically  modern   flora  had   been   evolved,  repre- 
sented, in  addition  to  the  trees  named  above,  by  the  wil- 
lows, oaks,  maples,  elms,  beeches,  chestnuts,  palms,  and 
numerous  other  forms.     It  is  a  fact  of  great  interest  that 
the  plants  of  this  period  occur  as  fossils  in  northern  lati- 
tudes all  around  the  world ;  and  we  may  be  quite  certain 
that  there  was  a  continuity  of  land  masses  in  the  vicinity' 
of  the  arctic  circle  at  that  time.     The  Sequoias,  which  are 
now  restricted  to  California  and  Oregon,  occur  as  fossils  in 
the  Cretaceous  strata  of  Greenland,  England,  France,  Ger- 
many, Italy,  Siberia,  Alaska,  and  Kansas.     The  northern 
hemisphere  at  that  time  was  like  a  vast  botanic  garden  in 
which  were  growing  side  by  side  plants  which  are  now  dis- 


356  Introduction  to   Botany. 

tributed  in  various  climes.  Cycads,  palms,  and  tree  ferns 
were  near  neighbors  to  oaks,  beeches,  and  chestnuts,  and 
with  them  were  found  the,  at  present,  cosmopolitan  Com- 
positae  and  Leguminosae. 

227.  Tertiary  Plants. — The  Cenozoic  era  began  with  the 
same  characteristics  which   distinguished  the  Cretaceous 
period.    Early  in  the  Tertiary  period  grasses  first  appeared, 
and  with  them  land  animals  made  a  notable  advance,  the 
ancestors  of  our  domestic  animals  then  distinctly  appear- 
ing.    By  the  middle  of  the  Tertiary,  grasses  were  carpeting 
the  earth  as  we  now  find  them.    The  climate  was  evidently 
becoming  cooler,  for  palms  and  other  tropical  forms  were 
growing   less    abundant.     Toward   the  close  of  the  Ter- 
tiary,  the   tropical   forms    had    become    appreciably   less 
numerous  in  the  north ;  and  we  may  be  certain  that  the 
lowering  of  the  temperature,  which  in  the  Quaternary  cul- 
minated in  the  glacial  period,  was  now  decidedly  manifest. 

228.  Exodus   Southward   in  the  Quaternary.  —  In   the 
Quaternary  period  occurred  the  notable  exodus  of  plants 
from  the  land  of  their  origin  in  the  north  southward  across 
the  continents  in  front  of  the  advancing  accumulation  of 
ice  and  snow.     The  cause  of  the  changed  conditions  which 
resulted  in  the  movement  of  glaciers  as  far  south  as  south- 
ern Illinois  and  northern  Kansas,  is  not  fully  determined ; 
but  there  is  no  doubt  that  such  glaciation  took  place  and 
produced  a  profound  effect  on  plant  distribution. 

In  North  America  there  were  no  barriers  to  prevent  the 
migration  of  plants  southward,  but  in  Europe  and  Asia 
the  east  and  west  trend  of  the  mountain  ranges  caused  the 
extinction  of  many  species  which  were  unable  to  maintain 
themselves  in  the  .cold  mountain  altitudes  long  enough  to 
start  their  progeny  on  the  southern  slopes.  Thus  the 
gigantic  Sequoias  (Fig.  193)  were  exterminated  in  Europe 


Plants  of  Past  Ages. 


357 


and  Asia,  but  were  able  to  find  a  congenial  home  in  Ore- 
gon and  California. 

In  all  probability  the  northern  flora  in  its  southern  migra- 
tion attempted  to  disseminate  itself  throughout  the  breadth 
of  the  continent,  but  some  forms  found  themselves  more 
readily  adaptable  to  the  Atlantic  slopes,  some  to  the  Mis- 
sissippi valley,  and  others  to  the  Rocky  Mountains  and 
the  regions  west,  so  that  now  we  find  more  or  less  distinct 


FIG.  193. 

Base  of  the  giant  Sequoia  "  General  Grant."     Photograph  by  SQUIRES. 

floras  in  these  different  regions.  Along  the  eastern  coast 
of  Asia,  including  the  Japan  islands,  the  physical  condi- 
tions approximated  those  of  our  Atlantic  slopes,  and  we 
find  that  in  these  regions,  remote  from  each  other,  very 
similar  floras  have  been  evolved  from  the  common  stock 
which  came  to  them  during  the  migration  in  the  glacial 
period. 

229.   Migration   Northward. — When,  for  some  reason, 


358  Introduction  to  Botany. 

the  conditions  changed  so  that  the  sun's  heat  was  able, 
finally,  to  melt  the  ice  back  to  the  arctic  regions,  and  the 
plant  pioneers  sought  to  occupy  again  the  land  from  which 
their  ancestors  had  been  driven,  the  mountain  barriers  in 
Europe  and  Asia  interposed  difficulties  to  which  the 
American  species  were  not  subjected.  The  greater  hard- 
ships in  both  Europe  and  Asia,  first  in  the  southern  and 
then  in  the  northern  migration,  have  resulted  at  the  pres- 
ent time  in  a  richer  flora  in  the  New  World  than  in  the 
Old.  There  is  evidence  that  man  himself  was  present 
during  at  least  a  part  of  the  Quaternary  period,  and  was 
a  witness  of  these  migrations,  which,  however,  doubtless 
took  place  very  slowly,  and  were  no  more  recognizable 
than  the  trend  of  plant  history  is  at  the  present  time. 

If  we  put  the  geological  record  in  evidence  along  with 
the  structural  affinities  of  plants,  we  find  we  have  reason- 
able ground  to  conclude  that  plants  have  evolved  from  the 
low  and  simple  types,  at  first  probably  of  microscopic  size, 
to  the  complex  forms  which  by  a  division  of  labor  among 
their  tissues  are  able  to  cover  the  surface  of  the  land,  and, 
rising  and  branching  in  the  atmosphere,  to  appropriate 
increased  amounts  of  the  sun's  energy ;  and  thus  while 
fulfilling  their  own  destiny  they  have  prepared  the  earth 
for  the  habitation  of  man. 


CHAPTER   XVII. 
CLASSIFICATION  OF  PLANTS. 

230.  Basis  of  Classification.  —  The  number  of  diverse 
plants  is  so  enormous  that  a  systematic  classification  is  a 
necessity  for  their  identification  and  for  a  concise  indica- 
tion of  their  relationships.  It  is  plain  that  since  plants 
are  descended  from  generation  to  generation  it  is  best,  if 
possible,  to  classify  them  according  to  their  lineal  descent ; 
those  plants  which  give  evidence  of  a  recent  common 
ancestor  being  placed  together  in  a  group,  and  assem- 
blages of  this  sort  which  appear  still  further  back  to  have 
descended  from  a  common  form,  being  classed  under  a 
still  more  comprehensive  family,  and  so  on  in  widening 
tribes  of  remoter  relationships  until  the  ultimate  groups 
are  finally  embraced  under  one  all-comprehensive  designa- 
tion, the  Vegetable  Kingdom.  Properly  to  determine  the 
degrees  of  relationship  among  plants  is,  in  many  cases, 
impossible,  and  our  classification  on  grounds  of  consan- 
guinity can  be  only  approximately  right. 

As  we  have  already  learned,  plants  have  been  subjected 
to  great  vicissitudes  in  their  long  residence  on  the  earth ; 
many  forms  have  become  extinct,  while  many  others  have 
wandered  far  from  their  ancestral  homes,  and  have  become 
profoundly  modified  under  changed  environments ;  and 
other  modifications  have  come  about  by  intercrossing.  The 
chain  of  evidence  may,  therefore,  be  incomplete  or  obscure. 
Where,  however,  forms  are  related  by  lineal  descent,  there 

359 


360  Introduction  to  Botany. 

are  certain  to  be  some  characteristics  common  to  all  which 
afford  satisfactory  evidence  of  the  relationship.  It  is  clear 
to  every  one  that  the  different  kinds  of  roses  are  nearly 
related ;  and  when  one  compares  the  flowers  and  fruits  of 
cherries  and  plums,  the  evidences  of  consanguinity  are  very 
striking,  but  the  points  of  similarity  between  roses  and 
cherries,  for  example,  are  fewer,  and  for  their  detection 
require  one  to  be  somewhat  familiar  with  the  proper  lines 
of  evidence. 

231.  Cause  of  Variation.  —  If  it  is  true  that   forms   of 
plants,  as  we  now  find  them,  have  descended  from  fewer 
and  simpler  primitive  types,  as  appears  to  be  the  case  from 
structural  evidence  and  geological  record,  then  an  inherent 
capacity  to  vary  under   changed   environment,   or  under 
other  conditions  which  we  do  not  understand,  must  be  one 
of  the  fundamental  causes  of  the  evolution  of  diverse  forms 
from  one  or  few  generalized  types ;   and  an  intercrossing 
between  forms  which  have   persisted  in  definite  lines  of 
variation  must  have  contributed  to  the  same  result.     Gaps 
occur  in  the  lineage  because  those  forms  whose  variations 
are  best  adapted  to  the  environment  have,  in  the  competi- 
tion for  room  and  food,  crowded  out  other  forms  less  favor- 
ably adapted.     It  is  these  gaps  which  enable  us  to  classify 
plants  into  more  or  less  circumscribed  groups.     We  can- 
not, of  course,  follow  plants  in  a  state  of  nature  from  gen- 
eration to  generation,  and  in  this  way  make  positive  record 
of  their  parentage  and  relationships.     We   have  to  take 
them  as  we  find  them,  and  classify  them  according  to  the 
circumstantial   evidence  of  their  similarities  and  dissimi- 
larities. 

232.  Grouping  into  Orders,  Genera,  etc.  —  In  classifying 
plants,  we  say  that  those  plants  belong  to  the  same  species 
which  are  so  nearly  alike  as  evidently  to  have  sprung  from 


Classification  of  Plants. 


36! 


seeds  or  asexual  propagative  bodies,  such  as  tubers, 
rhizomes,  etc.,  of  the  same  parent  plant,  or  from  different 
plants  which  in  their  turn  sprang  from  a  common  parent, 
and  so  on  back  for  an  indefinite  number  of  generations. 
Deviations  from  the  type  of  the  species  which  originate 
when  seeds  from  the  same  pod,  for  instance,  or  buds  from 
a  common  stock,  are  germinated  and  grown  under  different 
conditions  of  soil  or  cli- 
mate, are  called  varieties. 
Our  different  kinds  of 
cultivated  apples  and  po- 
tatoes are  good  exam- 
ples. Varieties  which 
tend  to  come  true  from 
seeds  are  called  races. 
Then  those  groups  of 
species  which  are  suffi- 
ciently alike  to  indicate 
a  common  ancestry  at 
some  time  in  their  his- 
tory are  classed  under 
one  genus  (plural,  gen- 
era}, and  the  groups  of 
genera  of  evident  rela- 
tionship are  classed  under  a  common  order,  or  family,  and 
so  on. 

We  may  find  good  illustrations  of  what  has  just  been 
said  in  the  different  kinds  of  wild  raspberries  and  black- 
berries. The  high  bush  blackberry,  Rubus  villosus  (Fig. 
194),  is  a  shrub  with  erect  or  recurved  stems  from  three 
to  four  feet  long,  having  stout  recurved  prickles ;  the  leaf- 
lets of  the  three  to  five  foliate  leaves  are  ovate  oblong,  with 
margins  closely  serrate  and  with  sharp  points,  and  they 


Rubus  villosus. 


FIG.  194. 
After  BRITTON  and  BROWN. 


362 


Introduction  to  Botany. 


are  pubescent  on  the  under  side.  The  flowers  are  white, 
from  three-fourths  to  one  inch  broad,  and  the  black  pulpy 
fruit  is  from  one-half  to  one  inch  long,  and  has  a  pleasant 
flavor.  The  individual  plants  are  essentially  alike,  their 
common  ancestry  is  very  evident,  and  we  class  them  ac- 
cordingly, under  one  species. 
The  running  swamp  black- 
berry, Rubus  hispidus  (Fig. 
195),  has  slender  creeping 
stems,  beset  with  weak  bris- 
tles. From  the  creeping  stems 
more  or  less  erect  branches, 
nearly  or  quite  destitute  of 
prickles,  arise  to  a  height  of 
four  to  twelve  inches,  and  bear 
leaves  of  three,  rarely  of  five, 
obovate  leaflets  whose  mar- 
gins are  irregularly  and 
sharply  serrate  above  the 
middle.  The  white  flowers 
are  one-half  to  two-thirds  of 
an  inch  across,  and  the  black, 
sour  fruit  is  less  than  one-half  inch  long. 

No  one  would  consider  that  these  two  blackberries  had 
arisen  by  suckers  or  seeds  from  the  same  stock,  and  they 
are  accordingly  classified  under  different  species ;  but  still 
they  have  so  many  structural  characteristics  in  common 
that  they  apparently  sprang  from  a  common  ancestor  some- 
where back  in  their  lineage.  We  note,  for  instance,  that 
each  has  flowers  consisting  of  a  deeply  five-parted  calyx 
with  a  shallow,  broad  tube ;  five  petals,  numerous  distinct 
stamens  inserted  on  the  calyx,  several  two-ovuled  carpels 
inserted  on  a  convex  receptacle,  which  in  ripening  become 


FIG.  195. 

Rubus  hispidus.     After  BRITTON  and 
BROWN. 


Classification  of  Plants.  363 

little  one-seeded  stone  fruits  or  druplets  that  adhere  and 
form  an  aggregate  fruit.  Because  of  these  similarities  we 
classify  them  under  the  same  genus,  Rubus.  Rubus  vil- 
losus  and  Rubus  hispidus  have  many  other  relatives  among 
'the  blackberries,  raspberries,  and  dewberries,  with  distinc- 
tive characters,  but  all  sufficiently  alike  to  indicate  a  close 
relationship. 

If  we  turn  to  the  strawberries  we  find  evidences  of 
relationship  between  them  and  the  blackberries  and  rasp- 
berries, the  flowers  of  the  strawberry  also  having  a  five- 
parted,  broad  and  shallow  calyx,  but  with  a  bract  between 
each  division ;  numerous  stamens  with  slender  filaments, 
numerous  carpels  on  a  convex  receptacle.  Thus  far  the 
resemblances  are  striking  and  afford  evidence  of  relation- 
ship ;  but  we  also  find  some  pronounced  dissimilarities,  — 
the  carpels  in  ripening  do  not  become  fleshy  stone  fruits, 
but  dry,  one-seeded  nutlets,  and  the  receptacle  grows  to  be 
large,  fleshy,  and  fragrant.  The  relationship  does  not 
seem  close  enough  to  class  the  strawberry  under  the  genus 
Rtibus,  and  we  accordingly  group  the  various  species  of 
it  under  the  genus  termed  Fragaria,  on  account  of  the 
fragrant  receptacle. 

The  similarities  which  we  find  between  the  raspberries, 
blackberries,  and  strawberries  indicate  a  remote  common 
ancestry,  and  we  therefore  place  the  genera  Rubus  and 
Fragaria  under  the  same  family,  Rosacecz,  rose  family. 
While  it  can  be  seen  that  a  classification  on  such  a  basis  is 
natural  in  contradistinction  to  artificial,  and  does,  to  a  large 
extent,  indicate  true  degrees  of  relationship,  yet  it  must  be 
a  matter  of  judgment  as  to  where  the  lines  shall  be  drawn 
between  species,  genera,  etc.,  which  must  be  more  or  less 
arbitrarily  exercised. 

There  are  still  more  comprehensive  grades  of  classifica- 


364  Introduction  to   Botany. 

tion  than  the  orders  or  families,  these  being  grouped  into 
sub-classes,  these  into  classes,  and  the  classes  into  sub- 
kingdoms,  which  finally  are  comprised  under  the  vegetable 
kingdom. 

233.  Best  Evidence  of  Relationship.  —  It  is  evident  that 
those  structures  which  are  apt  to  vary  considerably  under 
changed  environment,  in  the  lifetime  of  a  single  individual, 
do  not  furnish  good  evidence  as  to  relationships.  Thus, 
individuals  of  Helianthemum  vulgare,  which  are  known  to 
be  from  the  same  stock  and  consequently  of  the  same 
species,  exhibit  the  different  forms  shown  in  Fig.  191 
when  grown  at  different  altitudes.  It  is  seen  that  the  size 
and  habit  of  the  plant  are  greatly  altered,  while  the  char- 
acter of  the  flowers  is  quite  the  same.  Many  instances 
could  be  brought  forward  to  show  that  the  vegetative  parts, 
—  that  is,  those  parts  which  are  actively  concerned  in  the 
life  of  the  individual,  —  are  much  more  unstable  under 
changed  environment  than  the  reproductive  parts  which  do 
not  contribute  toward  the  maintenance  of  the  individual, 
but  are  only  concerned  with  the  continuance  of  the  species. 
It  is  because  of  the  greater  fixity  of  character  of  the  flowers, 
seeds,  and  fruits,  that  chief  reliance  is  to  be  placed  on  them 
in  determining  relationships. 


PART    II. 

THE    HERBARIUM,    LABORATORY    EQUIPMENT,    AND 
PROCESSES. 


CHAPTER   XVIII. 
THE   SCHOOL  HERBARIUM. 

234.  Character  of  the  Herbarium.  —  An  herbarium  containing  repre- 
sentatives of  the  most  interesting  plants  in  the  region  of  the  school  will 
be  found  useful  in  many  ways.  It  would  be  well  to  attempt  to  obtain 
the  complete  flora  of  the  region,  but  first  of  all  those  plants  and  parts  of 
plants  should  be  collected  which  possess  a  special  interest.  To  take  a 
single  illustration,  the  different  species  of  violets  growing  in  the  region 
should  be  represented  as  being  among  the  most  cherished  of  our  spring 
flowering  plants,  and  as  affording,  in  their  differences  and  similarities,  a 
good  idea  of  what  is  meant  by  species.  Those  plants  and  plant  parts 
should  be  represented  in  the  herbarium  which  best  show  the  different 
methods  of  securing  cross  fertilization,  of  scattering  seeds  and  fruits ; 
different  habits  of  climbing,  various  modes  of  protection  against  too 
rapid  transpiration,  or  against  mechanical  injuries. 

Plants  of  widely  different  habitats  should  be  represented,  such  as 
those  growing  in  dry  places,  in  moist  soil,  in  wet  places,  and  in  water. 
It  is  better  to  have  each  kind  of  plant  as  completely  represented  as 
possible,  the  plant  in  flower  being  accompanied  with  fruits,  seeds,  and 
seedlings.  It  is  readily  perceived  that  an  herbarium  which  is  thus  re- 
plete with  information  about  the  life  and  ways  of  plants  has  a  high 
educational  value.  Now  that  amateur  photography  has  become  so  gen- 
eral it  would  probably  not  be  difficult  to  have  the  herbarium  accom- 
panied with  photographs  of  plants  in  their  natural  habitat.  A  map  of 
the  region  might  also  be  prepared  with  the  habitat  of  the  different  plants 
indicated  thereon. 

Those  students  who  are  interested  in  making  private  collections 
should  be  encouraged  to  do  it,  but  it  is  perhaps  best  not  to  require  indi- 
vidual collections  of  students  as  an  organic  part  of  the  course ;  partly 
for  the  reason  that  a  large  part  of  such  work  is  merely  mechanical  and 
therefore  requires  time  that  could  be  more  profitably  spent  in  studying 
plants  as  living  beings.  The  few  students  who  would  cherish  such  col- 
lections and  profit  by  them  would  willingly  undertake  their  preparation 
as  extra  work. 

367 


3 68  Introduction  to  Botany. 

235.  Collecting  and  preparing  Materials. — In  collecting  materials 
for  the  herbarium,  a  tin  collecting  box  is  very  useful,  since  in  it  speci- 
mens may  be  kept  in  a  fresh  condition  for  two  days  or  longer.  The  col- 
lecting boxes  can  be  obtained  from  the  dealers  in  botanical  supplies,  or 
they  may  be  made  of  the  following  dimensions  at  the  tinners  :  Length 
17  inches  ;  diameters  of  ends,  which  are  oval,  4  by  6  inches  ;  on  one  of 
the  broad  sides  there  should  be  a  hinged  lid,  4}  by  15  inches,  fastening 
with  a  spring  catch ;  rings  should  be  soldered  on  near  the  ends,  to 
which  a  strap  could  be  fastened  for  suspending  the  case  over  the 
shoulders.  It  is  well  to  coat  the  case,  inside  and  out,  with  paint  or 
Japan  varnish.  For  digging  up  plants,  a  strong  garden  trowel  or  weed 
digger  is  very  serviceable. 

To  prepare^the  specimens  for  the  herbarium  they  should  be  spread  out 
between  two  sheets  of  thin  porous  paper  iii  inches  wide  by  16}  inches 
long,  called  specimen  sheets,  taking  care  that  the  parts  overlap  each  other 
as  little  as  possible,  and  that  the  leaves  are  not  crumpled,  and  then  the 
specimen  sheets  should  be  placed  between  two  or  more  sheets  of  thick 
carpet  or  blotting  paper,  termed  driers.  Specimens  thus  prepared  may 
be  stacked  one  above  another  to  the  depth  of  a  foot  or  so,  a  flat  board 
being  placed  on  top  of  the  pile,  and  on  the  board  rocks  or  other 
weights  amounting  to  40  or  50  pounds.  If  the  objects  are  too  long 
for  the  specimen  sheets,  they  may  be  bent  once  or  even  twice  like  the 
letter  N.  Thick  stems,  tubers,  etc.,  should  be  pared  down  to  requisite 
thinness,  but  so  as  to  preserve  their  form. 

The  damp  driers  should  be  replaced  by  dry  ones  every  day  for  about 
a  week,  or  until  the  specimens  appear  quite  dry.  The  damp  driers 
should  be  spread  out  in  the  sun  or  hung  about  a  stove,  and  it  were 
better  in  changing  the  driers  to  put  on  the  fresh  ones  while  they  are  still 
warm  from  this  treatment.  Some  plants  with  mucilaginous  juices,  such 
as  the  spiderworts,  dry  very  slowly  and  are  apt  to  discolor  badly.  This 
can  be  obviated  to  a  certain  extent  by  ironing  them  with  hot  irons 
while  lying  between  the  specimen  sheets.  Very  fleshy  plants  such  as 
the  cacti  should  be  slit  open  longitudinally  and  the  pulp  scraped  out  be- 
fore placing  them  in  the  press.  The  heads  of  composite  flowers  whose 
ray  florets  would  not  otherwise  come  under  pressure  in  the  press  should 
have  rings  of  cotton  placed  around  them  to  obviate  this  difficulty.  If 
parts  of  plants  must  necessarily  overlap  in  the  press,  pieces  of  porous 
paper  should  be  placed  between  them. 

When  dry  the  specimens  are  to  be  glued,  with  a  good  quality  of  pre- 


The  School   Herbarium.  369 

pared  fish  glue,  to  heavy  linen  ledger  paper  n^  by  i6£  inches  in  size. 
The  regulation  quality  and  size  of  this  paper  is  kept  in  stock  by  the 
dealers  in  botanical  supplies.  The  glue  should  be  thinly  spread  over 
the  back  of  the  specimen  with  a  soft,  flat  brush,  and  after  the  glued 
specimen  has  been  laid  in  position  on  the  herbarium  paper  a  sheet  of 
thin  paper,  and  then  a  flat  board  surmounted  by  a  weight,  should  be 
placed  over  it.  Many  sheets  with  specimens  attached  may  be  stacked 
in  this  way  while  the  glue  is  drying. 

The  name  of  the  plant  (genus  and  species  written  in  one  line),  should 
be  written  in  the  lower  right-hand  corner  of  the  herbarium  sheet,  to- 
gether with  the  locality  where  found  and  the  date  of  collection ;  the 
character  of  the  habitat  should  also  be  stated,  as,  for  instance,  whether 
the  soil  was  clayey  or  loamy,  wet  or  dry ;  whether  the  situation  was 
shady  or  fully  exposed  to  the  sun,  and  so  on.  The  name  of  the  collector 
should  also  be  given.  It  is  a  common  practice  to  have  labels  about  i| 
by  3f  inches,  with  the  name  of  the  collector  or  of  the  school  printed  in 
plain  letters  across  the  top,  and  on  these  to  write  the  name  of  the  plant 
and  other  data.  The  labels  should  be  made  of  strong,  but  thin,  white 
paper,  and  should  be  fastened  at  the  lower  right-hand  corner  of  the  her- 
barium paper  by  coating  them  thinly  with  glue  along  the  borders  only. 

One  species  only  should  be  mounted  on  a  single  sheet  of  herbarium 
paper ;  but  several  specimens  of  the  same  species,  illustrating  different 
stages  of  growth  or  variations  in  different  habitats,  might  well  be 
mounted  together,  each  specimen  being  accompanied  by  its  own 
record.  The  specimens  thus  prepared  are  then  to  be  inclosed  in  a 
folded  genus  cover  of  heavy  manila  paper,  which  should  be  about  \  inch 
broader  and  longer  than  the  herbarium  paper.  All  the  species  of  a 
genus  should  be  included  under  one  cover  unless  too  numerous. 

Ferns,  horsetails,  club-mosses,  and  other  Cryptogams  of  large  size 
should  be  pasted  to  the  herbarium  paper  in  the  same  manner  as 
described  above  for  Phanerogams.  The  horsetails  and  club-mosses 
are  apt  to  adhere  with  difficulty,  but  may  be  fastened  on  more  securely 
with  narrow  strips  of  gummed  paper.  Mosses,  liverworts,  Lichens,  and 
Fungi  in  general  should  be  inclosed  loosely  in  envelopes,  which  are  to 
be  glued  at  their  centers  .only  to  the  herbarium  paper.  The  envelopes 
can  be  made  in  any  desired  size  by  doubling  strong  and  thin  white 
paper,  folding  back  the  loose  top  edges,  and  folding  the  ends  under  for 
about  an  inch  of  borders. 

Delicate  Algae  demand  a  special  method  of  treatment.     Herbarium 


370  Introduction  to  Botany. 

paper  is  cut  into  pieces  4^5  by  5f  inches  in  size.  The  Alga  to  be 
mounted  is  placed  in  a  pan  of  water,  and  the  piece  of  herbarium  paper, 
while  resting  at  its  center  on  the  tips  of  the  fingers  and  thumb,  is  sub- 
merged beneath  the  Alga  and  carefully  brought  up  against  it,  care  being 
taken  as  the  paper  is  lifted  from  the  water  that  the  Alga  spreads  out 
equally  on  all  sides.  If  success  is  not  attained  at  first  the  process 
should  be  repeated  until  the  branches  of  the  Alga  are  symmetrically  dis- 
tributed. The  paper  is  then  laid  on  a  drier,  and  a  piece  of  old  muslin 
over  the  Alga,  and  then  over  all  a  drier,  board,  and  weight.  The  driers 
are  to  be  changed  as  usual,  but  the  cloth  is  not  to  be  removed  until  the 
specimen  is  dry.  When  dry,  the  Alga  sticks  to  the  herbarium  paper 
without  further  assistance,  but  not  to  the  cloth,  which  has  been  em- 
ployed for  that  reason. 

Very  delicate  specimens,  such  as  the  sporangia  of  some  Myxomy- 
cetes,  need  to  be  protected  against  crushing.  A  piece  of  the  sub- 
stratum to  which  they  are  growing,  such  as  a  dried  leaf,  twig,  or  rotting 
log,  should  be  glued  to  a  piece  of  cardboard,  and  then  strips  of  cork  or 
strawboard  should  be  fastened  to  the  card,  on  two  sides  of  the  speci- 
men, to  support  a  cardboard  cover.  Thus  protected,  the  specimen  is  to 
be  inclosed  in  a  folded  envelope  fastened  to  the  herbarium  paper  as 
already  described. 

It  is  the  practice  of  some  botanists  to  fasten  the  envelopes  contain- 
ing mosses,  etc.,  and  the  small  sheets  of  paper  on  which  the  Algae  are 
mounted,  to  herbarium  paper  n|  by  8£  inches  in  size,  which  is  just 
one-half  the  standard  size.  The  specimens  should  be  kept  in  dust- 
free  wooden  cases  or  tin  boxes.  A  wooden  case,  with  tightly  fitting 
door,  and  provided  with  thin  shelves  about  three  inches  apart,  is  very 
convenient. 


CHAPTER   XIX. 


LABORATORY  EQUIPMENT. 

236.  Tables. — In  a  school  where  the  study   of  plants   is  to  be 
seriously  pursued  there  should  be  a  working  room  equipped  with  tables 
of  such  size,  and  so  arranged,  as  to  give  the  students  plenty  of  room 
and  light  for  their  work.     The  ordinary  school  desks  are  not  of  suitable 
construction  and  arrangement  for  laboratory  work,  and  where  a  special 
laboratory  cannot  be  provided,  it  would  be  a  good  plan  to  fasten  boards, 
about  eighteen  inches  wide,  to  the  wall  beneath  the  windows,  by  means 
of  strong  brackets,  to  serve  as  working  tables.     Even  where  there  is  a 
special  workroom,  such  tables  will  be  found  very  serviceable.     The 
main  thing  in  any  case  is  to  have  a  flat  working  table,  well  lighted  by 
diffuse  light,  which  will  afford  plenty  of  elbow  room  for  each  student. 

237.  Microscopes.  —  Much  of  the   observation   in  an  introductory 
course  in  botany  can  be  done  with  the  naked  eye,  but  for  part  of  the 
work  a  good  simple  lens  is  a  neces- 
sity.1 It  is  economical  to  have  cheap 

pine  blocks  made  as  stands  for  the 

lenses,  after  the  manner  of  Fig.  196, 

rather  than  to  purchase  the  stands 

of  the  dealers.    Ordinary  2  by  4  inch 

pine   scantling  is   dressed  smooth, 

and  cut  into  two  lengths  of  8  and  3 

inches  respectively.      It  is  better  to 

bevel  the  ends  of  the  short  pieces. 

The  short  piece  (b}  is  to  be  fastened 

to  the  long  piece  (#),  as  shown  in 

Fig.  i,  by  means  of  glue  and  a  screw 

driven  through  from  the  lower  face 

of  the  long  piece.     A  brass  rod  (c)  about  ^  inch  in  diameter  and  3^ 

inches  long  is  driven  into  the  short  block,  as  seen  in  the  figure,  to  a 

1  The  doublet  lenses  manufactured  by  Bausch  &  Lomb,  Rochester,  N.Y., 
are  satisfactory  for  this  purpose,  those  of  |-inch  focal  length  being  the  best 
for  general  work. 

371 


FIG.  196. 

A  simple  dissecting  microscope. 
See  text. 


372 


Introduction  to  Botany. 


depth  of  I  inch — a  hole  of  slightly  smaller  diameter  having  first  been 
bored  to  receive  it.  Spring  brass  wire  of  ^j-inch  diameter  is  then  cut 
into  lengths  of  17  inches,  and  each  piece  shaped  to  serve  as  two  lens 
holders  according  to  the  following  directions  :  — 

Clamp  one  end  of  a  wire  nail  of  about  |£-inch  diameter  firmly  in  an 
iron  vise.  Place  the  brass  wire  with  its  middle  against  the  wire  nail, 
and  wrapping  from  both  ends,  make  a  coil  of  ten  turns  about  the  nail, 
and  cut  the  wire  in  two  at  the  middle  of  the  coil ;  then  at  i^  inches  from 
the  center  of  the  coil  of  each  half  bend  the  wire  into  a  loop  to  receive 
and  firmly  hold  the  doublet  lens.  When  completed  (</),  the  spiral  coil 
should  grip  the  rod  in  the  block  firmly  enough  to  hold  the  lens  at  any 
height,  but  without  binding  too  tightly  to  prevent  an  easy  vertical 
adjustment.  The  block  should  be  given  one  or  two  coats  of  shellac 
into  which  enough  lampblack  has  been  stirred  to  make  a  black  varnish. 
No  glass  stage  or  mirror  is  necessary,  for  the  shellac  affords  a  black 
background  against  which  thin  sections,  etc.,  are  strongly  contrasted. 

238.  Dissecting  Needles.  —  Dissecting  needles  can  be  made  as  fol- 
lows :  Grasp  a  strong  needle  in  a  pair  of  pliers  and  thrust  it,  eye 

foremost,  into  a  handle  of  soft  wood 
or  into  a  smooth  twig  with  very  small 
pith.  Hard  wood  handles,  such  as 
can  readily  be  prepared  from  butch- 
ers' skewers,  should  have  holes  drilled 
into  them  to  receive  the  needles.  A 
good  drill  for  this  purpose  is  made  by 
breaking  the  eye  from  a  needle  a  size 
larger  than  those  which  are  to  be  in- 
serted, and  rubbing  the  broken  end 
into  the  form  of  a  drill  point  on  an 
oil  stone.  The  needle  should  be 
pushed  into  the  handle  a  slight  dis- 
tance beyond  the  bottom  of  the  hole 
made  with  this  drill. 

239.  Manner  of  Using  Lenses.— 
For  much  of  the  work  requiring  the 
use  of  a  lens  the  dissecting  block  will 
not  be  needed,  the  lens  simply  being 

held  between  the  thumb  and  forefinger  of  one  hand  while  the  object 
is  held  in  the  other  hand  in  the  same  manner.  To  prevent  vibration, 


FIG.  197. 

Showing  the  manner  of  holding  lens 
and  object. 


Laboratory  Equipment.  373 

the  middle,  ring,  and  little  fingers  of  the  hand  holding  the  lens  should 
rest,  in  a  closed  position,  in  the  palm  of  the  hand  holding  the  object,  as 
shown  in  Fig.  197.  It  is  to  be  remembered  that  the  object,  and  not 
the  eye  or  the  lens,  should  receive  the  best  illumination ;  for  the  object 
becomes  visible  only  by  the  light  which  is  reflected  from  its  surface 
through  the  lens  and  into  the  eye.  The  best  light  is  that  which  comes 
over  the  shoulder  or  from  one  side,  and  the  student,  if  facing  a  window, 
should  turn  to  one  side  when  making  observations.  For  some  work 
the  dissecting  stands  are  a  great  convenience,  particularly  when  minute 
structures  require  separation  with  the  needles.  In  such  a  case  the 
object  should  lie  upon  the  dissecting  stage,  and  the  lens  should  be 
placed  in  the  wire  holder  and  adjusted  to  a  proper  height  to  give  a  sharp 
image  of  the  object ;  then  both  hands  will  be  free  to  manipulate  the 
specimen  with  the  needles  while  it  is  viewed  through  the  lens.  In 
using  the  needles,  the  hands  should  rest  upon  the  shelves  made  for  that 
purpose  at  the  ends  of  the  block. 

240.  Care  of  the  Lens. — The  lens  must  be  kept  clean  and  bright. 
It  will  be  noticed  that  if  the  fingers  come  in  contact  with  its  faces  a 
filmy  spot  is  left  which  excludes  much  of  the  light  when  the  lens  is 
again  used.     To  remove  such  spots,  breathe  upon  the  glass  and  quickly 
polish  it  with  a  clean  soft  cloth.     The  student  should  always  see  that 
the  lens  is  in  good  condition  before  using  it. 

241.  The  Compound  Microscope.  —  A  compound  microscope  is  not 
an  absolute  necessity  in  a  beginning  course  in  botany,  but  it  is  very  use- 
ful in  gaining  a  clear  comprehension  of  some  primary  facts  of  plant 
structure  and  physiology  with  which  the  student  should  early  become 
acquainted.     A  good  compound  microscope  with  a  very  satisfactory  out- 
fit can  now  be  purchased  by  schools  for  $25  or  less,  and  there  is  no 
reason  why  every  school  in  which  botany  is  taught  should  not  be  sup- 
plied with  at  least  one.     The  optical  parts  of  a  compound  microscope, 
which  are  most  useful  for  a  general  study  of  tissues  and  cell  contents, 
are  a    i-inch   eyepiece  and  a  f-inch    and  a  £-inch   objective.      The 
objectives  should  be  fastened  to  a  double  nosepiece  in  order  that  they 
may  quickly  be  shifted. 

242.  Use  of  Compound  Microscope. — When  thin  sections  or  very 
minute  objects,  such  as  starch  grains  or  cell  contents  in  general,  are 
being  studied,  the  object  should  be  seen  by  transmitted  light,  —  that  is, 
by  light  which  is  reflected  from  the  mirror  (0,  Fig.  198),  below  the  stage 
(«),  through  the  object  (/),  and  into  the  objective  (£).     The  surfaces 


374 


Introduction  to  Botany. 


of  opaque  objects  are  to  be  seen  by  light  which'  is  reflected  directly 
from  their  surfaces  into  the  objective.  The  compound  microscope  dif- 
fers from  the  simple  lens  essentially  in 
that  the  light,  which  passes  from  the 
object  into  the  objective,  is  brought  to 
a  focus  in  the  tube  of  the  microscope, 
at  the  level  of  the  eyepiece  diaphragm, 
forming  an  enlarged  real  image  (r), 
which  in  turn  is  magnified  by  the  eye- 
piece (/).  Thus,  the  eyepiece  serves 
as  a  simple  lens  and  magnifies  as  at  (J} 
an  enlarged  image  of  the  object.  It 
will  be  "seen  that  it  is  of  utmost  impor- 
tance that  the  lenses  of  eyepiece  and 
objectives  should  be  kept  perfectly 
clean,  otherwise  the  light  will  be  too 
much  absorbed  to  produce  a  clear  image. 
In  examining  cell  contents  or  thin  sec- 
tions of  plant  tissues  with  the  com- 
pound microscope,  the  objects  should  be 
mounted  in  a  drop  of  water  or  other 
reagent,  as  the  case  may  require,  on  a 
clean  glass  slip,  and  'covered  with  a 
perfectly  clean  coverglass. 

243.  Preparing  Material  for  Obser- 
vation.—  In  becoming  acquainted  with 
the  use  of  a  compound  microscope,  starch 
from  a  potato  will  do  for  examination. 
Having  washed  a  slip  and  coverglass  and 
polished  them  with  a  clean  cloth,  set 
the  coverglass  on  edge  until  wanted, 
and  lay  the  slip  flat  upon  the  table; 
then  cut  a  potato  in  two  and  scrape  off 
a  very  small  portion  of  the  pulp  with  the  point  of  a  penknife.  Trans- 
fer the  material  on  the  knife  to  a  small  drop  of  water  placed  at  the  center 
of  the  glass  slip,  and  cover  with  the  coverglass.  In  doing  this,  grasp 
the  coverglass  by  its  opposing  edges  between  the  thumb  and  forefinger, 
and  place  its  lower  edge  against  the  slip  a  little  to  the  left  (if  the  cover- 
glass  is  held  in  the  left  hand)  of  the  object ;  then  place  the  middle  finger 


FIG.  198. 

Diagram  of  a  Compound  Micro- 
scope, showing  the  manner  of 
the  formation  of  the  image. 
See  description  in  the  text. 


Laboratory  Equipment.  375 

of  the  hand  holding  the  coverglass  against  the  lower  edge  of  the  latter, 
to  keep  it  from  sliding  to  the  left ;  gradually  lower  the  coverglass,  giving 
it  additional  support  by  means  of  a  dissecting  needle  held  against  its 
lower  surface.  As  it  comes  in  contact  with  the  fluid,  see  that  no  air 
bubbles  become  entangled ;  if  there  seems  to  be  danger  of  this,  briskly 
move  the  coverglass  up  and  down,  by  means  of  the  dissecting  needle, 
until  the  bubbles  become  broken.  The  reason  for  lowering  the  cover- 
glass  gradually  instead  of  simply  dropping  it  over  the  object  is  to  pre- 
vent the  formation  of  bubbles,  which  would  make  the  preparation  more 
difficult  to  study. 

244.  Manipulating  the  Microscope.  —  Having  properly  mounted  the 
object,  place  the  slide  on  the  stage  (Fig.  198,  n)  of  the  microscope  so 
that  the  object  stands  over  the  center  of  the  opening  in  the  stage.  Set 
the  microscope  in  a  convenient  position  (an  upright  one,  when  the  ob- 
ject is  mounted  in  a  thin  fluid),  and,  by  means  of  the  concave  surface 
of  the  mirror,  reflect  diffuse  light  from  a  white  cloud  or  other  bright 
portion  of  the  sky  (never  use  direct  sunlight),  so  that  the  object  is  illu- 
minated from  below.  This  is  done  while  looking  directly  at  the  object 
outside  the  microscope.  When  the  object  is  seen  to  be  illuminated, 
swing  the  f-inch  objective  into  position,  and  rack  the  body  of  the 
microscope  down  until  the  front  face  of  the  objective  is  within  about 
I  inch  of  the  object ;  then  look  into  the  microscope  and  slowly  rack 
the  body  up  until  the  object  comes  into  focus.  Finally,  make  the 
image  sharp  by  means  of  the  micrometer-screw  fine  adjustment  (g). 
If  the  field  does  not  appear  bright  on  first  looking  through  the  micro- 
scope, only  a  slight  adjustment  of  the  mirror  is  likely  to  be  necessary. 
If  the  image  does  not  appear  as  the  body  of  the  microscope  is  drawn 
upward,  it  can  at  least  be  told  when  the  surface  of  the  coverglass  is  in 
focus,  by  means  of  flecks  of  dust  which  are  quite  certain  to  be  present, 
and  the  slide  can  then  be  moved  slowly  until  the  object  is  brought  into 
position. 

The  potato  pulp  will  appear  as  a  more  or  less  indistinct  mass,  but 
free  starch  grains  will  be  found  suspended  in  the  water.  Adjust  the 
slide  so  that  a  group  of  the  free  grains  is  exactly  in  the  center  of  the 
field,  rack  the  body  of  the  microscope  upward  and  swing  the  Hnch 
objective  into  position,  then  rack  downward  until  the  objective  nearly 
touches  the  coverglass.  In  racking  downward  always  observe  the 
objective  to  see  that  it  is  not  forced  against  the  coverglass.  Now 
look  through  the  microscope  and  raise  the  objective  by  means  of  the 


Introduction  to  Botany. 


micrometer  screw.  The  image  should  soon  appear,  for  the  f-inch 
objective  is  in  focus  when  its  front  lens  is  very  close  to  the  cover- 
glass. 

It  will  be  noticed  that  there  is  a  diaphragm  (111)  beneath  the  stage 
of  the  microscope,  with  openings  of  different  sizes,  or,  in  case  of  an  iris 
diaphragm,  with  a  single  opening  which  can  be  enlarged  or  contracted. 
The  larger  openings  give  greater  illumination,  and  the  smaller,  sharper 
definition.  It  is  a  good  rule  to  employ  the  smallest  opening  which  per- 
mits sufficient  illumination  with  a  given  object  and  source  of  light.  If 
the  diaphragm  is  of  the  revolving  kind,  care  must  be  taken  that  the 
opening  employed  is  centrally  placed,  as  indicated  by  the  stop  which 
clicks  into  position.  When  scraped  or  powdered  material  has  been 
mounted  in  a  drop  of  fluid  under  a  coverglass,  it  may  be  spread  out  in 
a  thin  even  layer  by  rubbing  the  coverglass  around  with  gentle  pres- 
sure, by  means  of  the  finger  covered  with  a  clean  cloth. 


FIG.  199. 

Positions  of  the  razor  with  reference  to  the  stem  in  cutting :  L,  a  cross  section ;  M, 
a  longitudinal  tangential  section  ;  N,  a  longitudinal  radial  section. 

245.  Cutting  Thin  Sections.  —  Thin  sections  need  to  be  cut  from  roots, 
stems,  leaves,  etc.,  in  order  to  study  their  cellular  structure.  In  the  case 
of  stems  and  roots,  cross  sections,  and  longitudinal  sections  through 
the  center,  called  longitudinal  radial  sections,  are  the  most  instructive, 
but  it  is  often  desirable  to  prepare  longitudinal  sections  outside  the 
center,  termed  tangential  sections  (Fig.  199).  In  the  case  of  leaves, 
cross  sections  of  the  blade,  at  any  desired  place,  answer  the  usual 
purposes. 

A  good,  half  hollow-ground  razor  — that  is,  one  with  a  thick  blade 
ground  slightly  concave  on  both  sides  —  is  more  effectual  in  section-cut- 
ting than  the  plano-concave  razors  sold  by  the  dealers  in  microscope 
supplies.  Material  which  is  fresh  may  be  sectioned  at  once,  but  dry 


Laboratory  Equipment. 


377 


material  should  be  well  soaked  in  warm  water  before  using.  It  is  still 
better,  after  soaking  dry  roots,  stems,  or  pieces  of  dry  wood,  to  place 
them  in  equal  parts  of  alcohol,  glycerine,  and  water,  for  a  week  or  so 
before  sectioning. 

To  cut  a  cross  section  of  a  stem  or  root,  trim  one  end  squarely  across 
with  a  sliding  stroke  of  a  sharp  knive ;  then  hold  the  object  between 
the  thumb  and  forefinger,  flood  the  upper  face  of  the  razor  with  water 
or  50  %  alcohol,  and  rest  it  on  the  forefinger  with  the  point  against  the 
object ;  regulate  the  thickness  of  the  section  to  be  cut  by  raising  or 
lowering  the  forefinger,  and  cut  the  section  with  a  long  forward  stroke 
(see  Fig.  200) .  The  sections  usually  need  to  be  made  as  thin  as  they 
can  possibly  be  cut.  The  upper  face  of  the  razor  is  kept  wet  in  order 


Showing  the  method  of  holding  the  object  and  razor  in  cutting  sections 
free-hand. 


that  the  sections  may  easily  slide  over  the  blade  without  crumpling  or 
rolling  up.  As  the  sections  are  cut,  they  should  be  transferred  to  a  dish 
of  water,  and  should  not  at  any  time  be  allowed  to  dry. 

Leaves  and  some  succulent  stems  and  roots  need  to  be  embedded  in 
elder  pith  before  sectioning,  and  for  such  purpose  a 
good  supply  of  dry  pith  should  be  kept  on  hand.  A 
piece  of  the  pith  not  more  than  an  inch  in  length  is 
halved  longitudinally  with  a  sliding  stroke  of  a 
knife,  while  held  on  a  table  firmly  between  the  thumb 
and  fingers  to  keep  it  from  breaking.  If  a  leaf  is  to 
be  sectioned,  a  strip  of  it  is  placed  between  the  pieces 
of  pith,  and  then  leaf  and  pith  are  sectioned  to- 
gether, the  razor  being  kept  wet  as  before,  preferably  Method  of  inclos- 
with  50%  alcohol.  If  succulent  stems  and  roots  are  ing  an  object  in 
to  be  sectioned,  longitudinal  V-shaped  grooves  are  cut 
in  both  pieces  of  pith,  of  proper  size  to  clamp  the  material  firmly 
(Fig.  201). 


FIG.  201. 


378 


Introduction  to  Botany. 


FIG.  202. 


Method  of  using  a  razor  on  a  simple 
microtome.    See  text. 


A  simple  microtome,  which  can  be  clamped  to  the  laboratory  table, 
will  be  found  of  great  service.1 

In  cutting  sections  with  such  an  instrument,  the  razor  is  to  be  held 

firmly,  edge  and  back,  against  the 
t  /  glass  top,  and  given  a  sliding  forward 
motion,  as  indicated  by  the  arrow  in 
Fig.  202.  The  object,  embedded  in 
elder  pith,  if  necessary,  is  clamped  in 
the  object  holder,  which,  as  the  sec- 
tions are  cut,  is  raised  by  means  of  a 
micrometer  screw  to  the  desired  thick- 
ness of  the  sections. 

246.  Mounting  the  Sections.  — As 
a  rule  a  section  should  be  mounted 
for  study  in  a  drop  of  water  under  a 
coverglass,  and,  if  reagents  are  to  be 
used,  they  are-'added  afterward.  The 
drop  in  which  the  section  is  to  be 
mounted  should  be  of  such  a  size 
that  it  will  fill  the  space  under  the 

coverglass  and  no  more ;  if  too  much  has  been  added,  draw  away  the 
surplus  with  filter  paper ;  if  not  enough,  place  a  small  drop  on  the  slip 
close  to  the  coverglass  on  the  side  where  the  water  comes  to  the  edge, 
and  then  draw  the  drop  into'  contact  with  the  coverglass  by  means  of 
a  dissecting  needle  or  small  stick.  If  the  drop  is  placed  at  first  in  con- 
tact with  the  'coverglass  it  may  run  over  its  upper  surface ;  if  it  is  placed 
on  the  side  where  the  water  does  not  fill  out  to  the  edge,  it  is  likely  to 
entangle  air  bubbles  when  it  runs  under.  If  no  reagents  are  to  be  used, 
the  preparation  may  be  kept  from  drying  by  applying  a  drop  of  50  % 
glycerine  to  one  edge  of  the  coverglass,  so  that  it  may  take  the  place 
of  the  evaporating  water. 

247.  Applying  Reagents.  —  Any  reagent  miscible  with  water,  such  as 
a  solution  of  iodine,  may  be  made  quickly  to  replace  the  water  in  which 
the  section  is  mounted,  by  placing  a  drop  of  the  reagent  on  the  slip  in 
contact  with  the  edge  of  the  coverglass,  and  then  placing  a  strip  of 
filter  paper  in  contact  with  the  opposite  edge  ;  in  this  way  the  water  is 
drawn  out  and  the  reagent  flows  in  and  occupies  its  place. 

248.  Sharpening  Knives  and  Razors.  —  No  satisfactory  results  can 

1  See  catalogue  of  Bausch  &  Lomb,  Rochester,  N.Y. 


Laboratory  Equipment. 


379 


be  obtained  in  section  cutting  without  sharp  knives  and  razors.  An  oil- 
stone should  therefore  be  provided,  and  a  fine  hone  and  strop  for  razors.1 
To  sharpen  an  ordinary  pocket  knife,  hold  the  under  face  of  the  blade  at 
an  angle  of  about  ten  degrees  with  the  stone,  and  impart  a  sliding  back 
and  forth  motion,  honing  the  two  sides  alternately  until  a  keen  edge  is 
produced,  keeping 
the  stone  well  oiled 
with  mineral  oil. 

The  razor  should 
be  kept  in  such  con- 
dition that  at  any 
place  on  its  edge  it 
will  readily  cut  in 
two  a  hair  held  be- 
tween the  thumb  and 


FIG.  203. 

Showing  how  to  draw  a  razor  over  the 
stone  in  honing  it. 


forefinger.  If  it  will 
not  do  this,  it  may 
only  need  stropping  on  the  prepared  leather  of  the  strop.  To  tell 
whether  it  should  be  honed  on  the  stone  before  stropping,  moisten 
the  ball  of  the  thumb  and  pass  it  with  gentle  pressure  longitudinally 
along  the  edge  of  the  razor  ;  if  the  edge,  throughout  its  length,  produces 

the  sensation  of  tak- 
ing hold  of  the  skin, 
the  use  of  the  stone 
will  not  be  necessary, 
but  otherwise  the 
razor  should  be 
honed  on  the  oil- 
stone until  it  re- 
sponds properly  to 
the  test.  In  honing, 


FIG.  204. 
Showing  how  to  draw  a  razor  over  the  strop. 


oil  the  stone  with 
mineral  oil ;  hold  the  blade  of  the  razor  flat  on  the  stone  and  slide  it 
edge  foremost  along  the  full  length  of  the  stone,  imparting  a  longitudi- 
nal as  well  as  a  forward  motion  to  the  razor,  so  that  it  glides  for  its  full 
length  from  point  to  heel  over  the  stone,  as  shown  in  Fig.  203.  Then 
turn  the  razor  on  its  back,  so  that  the  other  side  lies  on  the  stone,  and 
slide  the  razor  forward  and  longitudinally,  edge  foremost,  as  before. 

1  One  of  the  best  for  this  purpose  is  the  Torrey  combination  strop  and  hone. 


380  Introduction  to  Botany. 

When  the  honing  is  completed,  wipe  the  oil  from  the  blade  and  strop 
the  razor  on  the  prepared  leather  strop,  holding  it  flat  upon  the  strop, 
and  pushing  it,  back  foremost,  along  the  strop,  at  the  same  time  draw- 
ing it  from  heel  to  point  for  its  full  length,  as  shown  in  Fig.  204.  Then 
turn  it  on  its  back  and  repeat  the  process  for  the  other  side.  The  strop- 
ping should  be  done  quite  briskly,  but  with  gentle  pressure,  and  should 
be  continued  until  the  razor  readily  cuts  a  hair.  If  a  razor  needs  honing 
on  a  stone,  it  is  waste  of  time  to  try  to  give  it  a  proper  edge  on  the 
strop  without  first  honing  it. 


CHAPTER   XX. 
REAGENTS  AND  PROCESSES. 

Chloral  Hydrate.  —  Dissolve  8  parts  of  chloral  hydrate  in  5  parts  of 
distilled  water, — namely,  in  the  proportion  of  8  grams  of  chloral  hydrate 
to  5  grams  or  5  cubic  centimeters  of  distilled  water  (since  i  cubic  centi- 
meter of  distilled  water  weighs  i  gram).  Used  to  clear  plant  tissues,  or, 
in  conjunction  with  iodine,  to  demonstrate  the  presence  of  starch  in 
leaves,  etc.  (See  Chloral  Hydrate-Iodine.)  Whole  leaves  and  thick 
sections  can  be  very  quickly  cleared  by  boiling  in  this  solution. 

Chloral  Hydrate-Iodine.  —  Dissolve  5  parts  by  weight  of  chloral 
hydrate  in  2  parts  by  weight  of  a  weak  solution  of  iodine.  (See  Iodine 
Solution.) 

In  using  this  reagent  as  a  test  for  starch  in  thin  sections  of  leaves, 
etc.,  mount  the  section  in  a  drop  of  water  under  a  coverglass ;  focus 
the  section  with  a  high-power  objective  ;  place  a  drop  of  the  solution  on 
the  glass  slip  in  contact  with  the  edge  of  the  coverglass,  and  place  a 
piece  of  filter  paper  in  contact  with  the  opposite  side  of  the  coverglass. 
In  this  way  the  solution  will  be  drawn  under  the  coverglass,  and  its 
progressive  action  in  clearing  the  section  and  staining  the  starch  can  be 
followed. 

Chloroiodide  of  Zinc.  (Chlor-zinc  iodide.)  —  Dissolve  zinc  to  satura- 
tion in  concentrated  hydrochloric  acid  and  evaporate  the  solution  to  the 
consistency  of  concentrated  sulphuric  acid.  Add  potassium  iodide  to 
saturation,  and  then  as  much  iodine  as  can  be  taken  up.  The  solution 
should  have  a  decidedly  reddish  brown  color. 

Since  only  a  small  quantity  of  this  reagent  is  likely  to  be  needed,  it  is 
perhaps  best  to  buy  it  ready  prepared,  from  dealers  in  microscope  sup- 
plies. It  should  be  kept  in  the  dark,  well  stoppered.  By  this  reagent 
cellulose  membranes  are  stained  violet  to  purple.  Starch  is  stained  the 
same  color  and  swollen.  Lignified,  corky,  and  cutinized  membranes  are 
stained  a  golden  yellow.  Proteid  cell  contents  and  protoplasts  are 
stained  yellow  to  brown.  It  can  be  used  in  connection  with  phloro- 
glucin,  as  described  under  that  reagent. 


382  Introduction  to  Botany. 

Chrom-Acetic  Fixative.  —  Dissolve  I  gram  of  chromic  acid  in  100 
cubic  centimeters  of  distilled  water,  and  add  0.5  gram  of  glacial  acetic 
acid. 

When  it  is  desired  to  study  the  construction  of  the  protoplasts  in 
embryonic  tissues,  as  in  root  and  shoot  tips,  or  in  Algae,  Fungi,  etc.,  the 
fresh  material  should  be  submerged  in  the  above  killing  and  fixing  solu- 
tion from  i  to  2  days.  By  this  treatment  the  protoplasts  will  be  made 
to  keep  the  form  which  they  had  while  living.  The  fixative  should 
penetrate  the  material  quickly,  so  that  root  and  shoot  tips  should  be 
hardly  more  than  3  millimeters  or  |  inch  long.  Anthers  and  ovaries 
should  be  cut  open  at  both  ends.  Ovules  should  be  removed  from  the 
ovary  with  only  a  narrow  strip  of  tissue  adhering  to  them.  Leaves 
should  be  cut  into  narrow  strips,  not  more  than  3  millimeters  broad,  etc. 

A  relatively  large  amount  of  the  fixative  should  be  used ;  for  example, 
to  a  depth  of  4  centimeters  in  a  test  tube  2  centimeters  in  diameter, 
for  fixing  about  10  root  tips. 

After  fixing  the  material  tie  it  up  in  thin  muslin  and  wash  for  6  hours, 
or  over  night,  in  running  water,  or  in  water  which  is  frequently  changed. 
Then  gradually  dehydrate  and  harden  the  material  by  keeping  it  for  2 
hours  in  each  of  the  following  grades  of  alcohol :  20%,  30%,  40%,  50%, 
60%,  70%.  It  may  then  stay  in  70%  alcohol  until  wanted.  If  it  is  to  be 
kept  a  long  while  before  using,  it  would  be  better  to  take  it  from  the 
70%  alcohol  and  preserve  it  in  equal  parts  of  95  %  alcohol,  glycerine,  and 
water.  If  the  material  is  to  be  stained  with  safranin  (which  see),  or 
first  sectioned  and  then  stained,  it  may  go  directly  into  the  stain  from 
50  %  or  70  %  alcohol,  or  from  the  mixture  of  alcohol,  glycerine,  and  water ; 
and  then  may  be  mounted  for  immediate  study  in  equal  parts  of  glycer- 
ine and  water,  or  it  may  be  mounted  permanently  in  glycerine  jelly 
(which  see). 

It  is  frequently  very  desirable  to  embed  root  and  shoot  tips,  anthers, 
ovaries,  ovules,  etc.,  in  paraffin  preparatory  to  cutting  very  thin  and 
serial  sections  of  them.  To  learn  how  to  do  this  read  under  Imbedding 
in  Paraffin,  and  Cutting  Paraffin  Sections. 

Cutting  Sections.  —  Directions  for  cutting  sections  free-hand  will  be 
found  on  page  376. 

Sections  from  hard  tissues,  such  as  the  shells  of  nuts,  may  be  cut  as 
thin  as  possible  by  means  of  a  hack  saw,  and  then  brought  to  the  neces- 
sary thinness  between  two  oil  stones,  using  water,  instead  of  oil,  as  a 
lubricant. 


Reagents  and  Processes.  383 

Cutting  and  Mounting  Paraffin  Sections. —  For  cutting  paraffin 
sections  some  form  of  microtome  must  be  used.1  The  smaller 
student  forms  may  be  made  to  perform  very  efficient  service  in  paraffin 
sectioning. 

After  the  material  has  been  imbedded,  as  described  under  Imbedding 
in  Paraffin,  page  386,  cut  out  a  small  block  of  paraffin  containing  the 
object  to  be  sectioned  ;  melt  a  small  piece  of  paraffin  on  the  end  of  a  pine 
block  i  centimeter  square  in  cross  section  and  about  2  centimeters  long, 
and  while  the  paraffin  on  the  end  of  this  stick  is  still  melted,  press  into 
it  and  firmly  against  the  stick  the  paraffin  block  containing  the  object. 
The  paraffin  block  should  be  so  placed  on  the  stick  that  when  the  latter 
is  fastened  upright  in  the  object  carrier  of  the  microtome,  the  microtome 
knife  will  cut  the  sections  in  the  desired  direction  through  the  object. 
Heat  a  wire  nail  or  dissecting  needle,  and  melt  the  base  of  the  paraffin 
block  superficially,  to  seal  it  more  firmly  to  the  stick.  Submerge  the 
stick  in  cold  water  to  harden  the  paraffin,  and  fasten  it  in  the  object 
carrier  of  the  microtome,  having  first  set  the  carrier  near  its  lowest 
position.  Adjust  the  stick  so  that  the  top  of  the  paraffin  block  just 
touches  the  under  surface  of  the  knife.  Set  the  knife  at  right  angles  to 
the  bed  of  the  microtome.  Trim  the  face  of  the  paraffin  block  which 
faces  the  knife  parallel  with  the  edge  of  the  knife,  and  to  about  i  milli- 
meter from  the  object,  and  trim  the  opposite  edge  of  the  block  in  the 
same  manner,  so  that  the  two  edges  are  parallel,  and  parallel  to  the 
knife  edge.  Then  trim  the  remaining  two  sides  of  the  block  rather 
close  to  the  object.  The  sections  should  now  adhere  in  a  ribbon  as  they 
are  cut ;  10  micromillimeters  is  a  good  average  thickness  for  the  sections 
(i  micromillimeter  =  I^nf  millimeter).  In  wielding  the  knife  see  that 
the  knife  carrier  runs  easily  in  its  bed  (using  oil  if  necessary),  rest  the 
elbow  upon  the  table,  and  make  short  strokes  with  a  wrist  motion 
simply.  Transfer  the  ribbons  of  sections  to  a  clean  tray,  keeping  the 
side  down  which  was  down  in  cutting,  and  finally  mount  the  sections  on 
the  glass  slip  in  the  same  position. 

To  mount  the  sections  on  a  glass  slip,  spread  a  few  drops  of  albumen 
water  over  that  portion  of  the  slip  which  is  to  be  occupied  by  the 
sections,  the  slip  having  first  been  washed  with  soap  and  water,  rinsed, 
and  polished  by  rubbing  it  vigorously  with  a  clean  cloth.  If  the  albumen 
water  has  a  tendency  to  creep  away  from  the  place  where  it  has  been 

1  For  description  of  microtomes  see  catalogue  of  Bausch  &  Lomb,  Roch- 
ester, N.Y. 


384  Introduction  to  Botany. 

spread  out,  the  slip  has  not  been  thoroughly  cleaned.  It  is  a  good 
plan  to  keep  the  slips  in  concentrated  sulphuric  acid  saturated  with 
bichromate  of  potash  contained  in  a  pint  Mason  jar,  and  then  to  rinse 
and  polish  them  as  needed.  The  albumen  water  is  made  as  needed 
from  a  stock  solution.  To  make  the  stock  solution,  shake  together 
equal  parts  of  the  white  of  one  egg  and  glycerine,  and  add  to  this  mix- 
ture a  small  amount  of  salicylate  of  soda  to  keep  it  from  spoiling.  Allow 
the  mixture  to  stand  over  night  in  a  tall  cylinder,  and  skim  off  the  im- 
purities which  rise  to  the  top.  To  make  the  albumen  water,  add  I 
drop  of  the  stock  solution  to  about  10  cubic  centimeters  of  distilled 
water.  Make  the  albumen  water  afresh  every  few  days,  as  the  old 
solution  becomes  turbid  or  is  found  to  contain  a  precipitate. 

Having  spread  the  albumen  water  on  the  glass  slip,  cut  a  piece  of  the 
desired  length  from  the  ribbon  of  sections  and  lay  it  upon  the  albumen 
water,  and  so  on  until  nearly  the  entire  breadth  of  the  slip  is  occupied, 
in  case  rectangular  coverglasses  are  used  and  it  is  desired  to  study  the 
sections  in  series  in  the  order  in  which  they  were  cut.  With  a  piece  of 
filter  paper  filter  away  most  of  the  albumen  water,  and  while  doing  it 
arrange  the  sections  at  the  center  of  the  slip.  Then  place  the  slip  to 
dry  on  the  copper  plate  of  the  paraffin  imbedding  apparatus  described 
under  Imbedding  in  Paraffin.  Place  asbestos  paper  or  felt  paper  be- 
tween the  slip  and  the  copper  plate  until  the  slip  is  heated  to  a  little 
below  the  melting  point  of  the  paraffin.  It  is  best  to  let  the  slips 
remain  thus  for  an  hour  or  more. 

Before  staining  the  sections  stand  the  slide  on  end  in  a  tumbler  of 
xylene  to  dissolve  the  paraffin.  (After  the  sections  have  been  mounted 
on  the  slip  it  is  the  custom  to  call  the  entire  preparation  a  slide.)  The 
sections  should  adhere  to  the  slip  during  this  and  all  subsequent  manipu- 
lations. Rinse  off  the  xylene  in  a  tumbler  of  95  %  alcohol  and  stain  the 
sections  as  directed  under  Staining  and  Sealing  in  Balsam. 

Cyanin  and  Erythrosin  for  Double  Staining.  —  Sections  of  plant 
tissues  having  both  cellulose  and  lignified  walls  may  be  double  stained 
in  the  following  manner:  Place  the  sections  for  a  few  hours  or  over 
night  in  a  saturated  solution  of  cyanin  in  95  %  alcohol ;  then  rinse  the 
sections  in  a  dish  of  95  %  alcohol  until  the  cyanin  ceases  being  washed 
out  in  clouds.  (This  should  be  within  a  few  moments.)  Then  trans- 
fer the  sections  to  a  saturated  solution  of  erythrosin  in  clove  oil.  Leave 
them  there  only  a  moment  and  then  place  them  in  a  dish  of  xylene  and 
mount  almost  immediately  in  Canada  balsam  as  described  under  Stain- 


Reagents  and   Processes.  385 

ing  and  Sealing  in  Balsam.  By  this  process  of  staining  the  lignified 
walls  should  be  blue  and  the  cellulose  walls  red.  If  a  proper  differ- 
entiation is  not  obtained  by  the  time  ratios  here  given,  a  little  experi- 
mentation will  show  what  the  time  ratios  should  be  for  the  specific 
material. 

Fehling's  Solution  for  Demonstrating  Grape  Sugar  (Glucose) .  — 
Make  three  stock  solutions,  which  are  to  be  preserved  in  separate 
bottles. 

1.  17.5  grams  of  copper  sulphate  dissolved  in  500  cubic  centimeters 
of  distilled  water. 

2.  86.5  grams  of  sodium-potassium-tartrate  (Rochelle  salts)  in  500 
cubic  centimeters  of  distilled  water. 

3.  60  grams  of  sodium  hydrate  in  500  cubic  centimeters  of  distilled 
water. 

To  prepare  for  use,  mix  I  volume  of  each  of  the  three  stock  solu- 
tions with  2  volumes  of  distilled  water;  for  example,  mix  10  cubic 
centimeters  of  each  of  the  solutions  with  20  cubic  centimeters  of  water 
(50  cubic  centimeters  in  all).  The  mixture  should  have  a  clear  blue 
color. 

Place  the  material  to  be  tested  in  the  mixture  in  a  test  tube  and  boil 
for  a  few  moments.  If  glucose  is  present,  a  red  or  orange  precipitate 
of  cuprous  oxide  will  be  formed. 

Glycerine  Jelly.  —  Soak  for  2  hours  6  parts  by  weight  of  best 
gelatine  in  2  parts  by  weight  of  distilled  water,  and  add  7  parts  by 
weight  of  pure  glycerine.  Add  to  each  100  grams  of  this  i  gram  of 
crystallized  or  concentrated  carbolic  acid.  Warm  the  mixture  over  a 
water  bath  and  stir  it  until  it  is  clear.  Then  strain  it  through  filter 
paper  placed  in  a  funnel  in  a  steamer  or  incubator  to  keep  the  mixture 
fluid  enough  for  filtering.  Wet  the  filter  paper  with  distilled  water 
before  pouring  in  the  mixture.  Keep  the  jelly  well  stoppered  and  free 
from  dust. 

This  is  an  excellent  mounting  medium  for  microscope  objects.  Use 
it  as  follows :  Put  a  small  piece  of  the  jelly  on  a  glass  slip  and  slowly 
warm  the  slip  over  the  flame  of  an  alcohol  lamp,  or  other  suitable  flame, 
until  the  jelly  melts.  Then  place  in  the  melted  jelly  the  material  to  be 
mounted,  which  has  first  been  brought  into  concentrated  glycerine  as 
directed  under  Safranin.  Clean  and  warm  a  coverglass  and  carefully 
place  it  over  the  preparation  by  standing  it  on  one  edge  and  gradually 
lowering  it  so  as  not  to  entangle  air  bubbles.  (See  directions  for  doing 


386  Introduction  to   Botany. 

this  on  page  374.)  The  jelly  hardens  on  cooling  and  holds  the  cover- 
glass  firmly.  After  a  few  months  the  edge  of  the  coverglass  should  be 
cemented  to  the  slip  by  a  thick  solution  of  shellac  in  95  %  alcohol,  add- 
ing to  each  10  cubic  centimeters  of  the  solution  7  drops  of  castor  oil. 

Imbedding  in  Paraffin.  —  If  material  is  to  be  imbedded  in  paraffin, 
it  must  be  passed  from  the  70%  alcohol,  or  the  mixture  of  alcohol, 
glycerine,  and  water  (see  under  Chrom-Acetic  Fixative),  through  gradual 
degrees  of  concentration  into  a  solvent  of  paraffin,  such  as  chloro- 
form, and  finally  into  pure  paraffin  having  a  melting  point  close  to 
52°  C.  Proceed  as  follows:  From  the  70%  alcohol,  or  from  the 
alcohol,  glycerine,  and  water  mixture,  transfer  the  material  suc- 
cessively to  80%  alcohol,  95%  alcohol,  absolute  alcohol,  equal  parts 
of  absolute  alcohol  and  chloroform,  pure  chloroform,  a  second  pure 
chloroform,  leaving  it  in  each  grade  about  2  hours.  Then  transfer 
the  material  to  a  vial,  and  pour  over  it  enough  chloroform  to  cover  it, 
but  no  more,  and  add  a  shaving  of  paraffin.  Continue  to  add  paraffin, 
a  little  at  a  time,  until  no  more  can  be  dissolved  at  the  room  temper- 
ature. Now  place  the  vial  on  the  copper  plate  of  the  paraffin  bath 
described  below,  with  enough  asbestos  paper  or  felt  paper  between  it 
and  the  plate  to  keep  it  just  below  the  melting  point  of  pure  paraffin, 
and  add  a  few  more  bits  of  paraffin  to  the  vial.  Leave  the  vial  stand- 
ing thus  until  the  chloroform  is  entirely  evaporated,  which  will  be  when 
the  paraffin  no  longer  has  a  sweetish  taste.  If  the  paraffin  should  tend 
to  solidify  while  driving  off  the  chloroform,  remove  some  of  the  paper 
separating  the  vial  from  the  copper  plate,  for  the  paraffin  should  be 
kept  in  a  fluid  state.  Pour  the  material,  paraffin  and  all,  into  the 
dish  of  paraffin  of  the  paraffin  bath,  and  leave  it  there  from  24  to  48 
hours  in  order  thoroughly  to  infiltrate  the  tissues  with  the  paraffin. 
Then  pour  the  material  and  melted  paraffin  into  a  small  paper  tray, 
made  by  turning  up  the  edges  of  stiff  writing  paper  for  about  half  an 
inch.  Heat  dissecting  needles  in  a  blue  flame,  and  arrange  the  mate- 
rial in  orderly  rows,  leaving  enough  space  between  the  pieces  so  that 
each  piece  can  be  cut  from  the  block  with  a  good  border  of  paraffin 
about  it.  Now  float  the  tray  in  a  dish  of  cold  water ;  blow  upon  the 
surface  of  the  paraffin  to  harden  it ;  and  submerge  the  tray  as  soon  as 
the  surface  film  of  paraffin  can  bear  the  weight  of  the  water.  In  cut- 
ting out  a  piece  of  paraffin  with  an  object  imbedded  in  it,  preparatory 
to  mounting  it  on  a  microtome  (see  under  Cutting  and  Mounting  Paraf- 
fin Sections),  score  the  paraffin  block  deeply  on  both  sides  with  a  knife 


Reagents  and  Processes.  387 

in  order  to  keep  it  from  cracking  across  the  other  specimens  in  the 
block. 

The  paraffin  bath  can  be  simply  made  and  operated  as  follows : 
Nearly  fill  a  tumbler  or  other  relatively  tall  dish  with  melted  paraffin, 
and  after  the  paraffin  has  hardened,  set  a  copper  plate  over  the  tumbler, 
and  leave  one  corner  of  the  plate  projecting  far  enough  to  permit  a 
Bunsen  burner  or  kerosene  lamp  to  be  placed  under  it.  The  flame 
should  be  kept  at  a  height  to  melt  the  paraffin  to  a  depth  of  about  half 
an  inch.  When  the  material  which  has  been  gradually  brought  into  con- 
centrated paraffin  as  above  directed  is  poured  into  the  melted  paraffin 
of  the  bath,  it  will  sink  to  the  bottom  of  the  melted  portion,  where  its 
infiltration  will  be  completed  just  at  the  temperature  of  the  melting 
paraffin  ;  which  is  as  it  should  be. 

The  object  of  gradually  bringing  the  material  into  a  solvent  of  par- 
affin and  of  infiltrating  with  paraffin  slowly  is  to  keep  the  protoplasts 
from  shrinking  together  and  to  make  the  infiltration  more  complete. 

Iodine  Solution. — Dissolve  0.5  gram  of  potassium  iodide  in  a  few 
cubic  centimeters  of  water,  and  add  iodine  until  no  more  can  be  taken  up. 
As  a  reagent  for  starch,  dilute  to  a  light  brown  color.  For  demonstrat- 
ing proteids  and  protoplasts,  dilute  much  less  than  for  starch,  —  namely, 
to  a  red-brown  color.  By  this  reagent,  starch  is  stained  violet  to  dark 
blue,  and  proteids  and  protoplasts  yellow  to  brown.  Lignified,  cutin- 
ized,  and  corky  membranes  are  stained  yellow. 

Lime  Water.  —  Pound  up  unslaked  lime ;  place  this  in  a  bottle  to 
one-third  its  capacity,  fill  the  bottle  with  water,  cork*  it  and  shake 
thoroughly.  Keep  the  bottle  stoppered,  and  after  the  lime  has  settled 
decant  or  filter  off  the  clear  liquid.  Keep  in  a  tightly  stoppered  bottle. 
Used  to  demonstrate  CO2,  which  combines  with  it  to  form  a  white  pre- 
cipitate of  calcium  carbonate.  • 

Phloroglucin.  —  Dissolve  in  15  cubic  centimeters  of  95%  alcohol  as 
much  phloroglucin  as  is  held  on  the  point  of  a  penknife.  Use  as  a 
test  for  lignified  membranes  in  the  following  manner :  Place  the  mate- 
rial to  be  studied  in  the  solution  for  a  few  moments  ;  then  transfer  to  a 
drop  of  water  on  a  glass  slip,  and  put  on  a  coverglass.  Place  a  drop 
of  concentrated  hydrochloric  acid  on  the  slip  in  contact  with  the  cover- 
glass.  As  the  acid  diffuses  through  the  water,  the  lignified  membranes 
will  be  stained  pink. 

The  cellulose  tissues  of  the  section  may  now  be  stained  purple  by 
replacing  the  reagent  under  the  coverglass  with  chloroiodide  of  zinc. 


388  Introduction  to   Botany. 

To  do  this,  place  a  drop  of  chloroiodide  of  zinc  on  the  slip  in  contact 
with  the  coverglass,  and  place  a  piece  of  filter  paper  in  contact  with 
the  opposite  side  of  the  coverglass.  By  this  means  the  acid  will  be 
drawn  from  under  the  coverglass  and  the  chloroiodide  of  zinc  will 
occupy  its  place. 

Safranin.  —  Dissolve  safranin  to  saturation  in  95  %  alcohol  and  dilute 
with  an  equal  bulk  of  distilled  water.  This  is  very  useful  in  staining 
sections  of  plant  tissues,  or  for  staining  unicellular  or  filamentous  Algae 
or  Fungi  which  have  been  fixed  in  chrom-acetic  fixative  (which  see). 
The  material  should  lie  in  the  stain  over  night,  or  even  for  24  hours.  It 
should  then  be  transferred  to  a  small  amount  of  50%  alcohol,  and  strong 
alcohol  added  to  this  drop  by  drop  until  the  color  in  the  material  has  a 
transparent  quality,  but  is  still  quite  evident.  The  material  may  now 
be  mounted  in  a  drop  of  dilute  glycerine  under  a  coverglass  for  imme- 
diate study  with  a  microscope,  or  permanent  mounts  may  be  made  in 
glycerine  jelly  as  follows  :  Transfer  the  material  from  the  alcohol  rins- 
ing bath  to  equal  parts  of  glycerine  and  water,  and  leave  it  in  a  place 
free  from  dust  until  the  glycerine  has  become  concentrated  by  the  evap- 
oration of  the  water.  Then  mount  it  in  glycerine  jelly,  as  described 
under  that  head. 

Staining  Paraffin  Sections,  and  Sealing  in  Balsam.  —  Having  mounted 
paraffin  sections  as  directed  under  Cutting  and  Mounting  Paraffin  Sec- 
tions, and  having  dissolved  away  the  paraffin  in  xylene  and  rinsed  off 
the  xylene  with  95  %  alcohol,  as  there  directed,  the  slides  may  be  set  in 
a  tumbler  or  Stender  dish  containing  safranin,  for  about  6  hours,  or  over 
night,  then  quickly  rinsed  in  95  %  alcohol,  then  placed  in  a  tumbler  of 
xylene,  thence  mounted  in  balsam  as  directed  below.  Or  the  sections 
may  be  double  stained  with  cyanin  and  erythrosin,  practically  as  directed 
under  that  head ;  leaving  the  slides  over  night  in  a  tumbler  of  cyanin 
solution,  then  rinsing  in  a  tumbler  of  95  %  alcohol ;  by  means  of  a  drop 
tube  covering  the  sections  with  clove  oil  saturated  with  erythrosin,  while 
holding  the  slide  horizontal ;  after  a  moment  draining  off  the  clove  oil 
and  rinsing  the  slide  in  xylene,  and  then  sealing  the  preparation  in 
balsam. 

But  where  the  embryonic  tissues  of  root  and  shoot  tips,  and  develop- 
ing pollen  grains,  ovules,  etc.,  are  to  be  studied  with  special  reference  to 
the  construction  and  behavior  of  the  protoplasts,  the  most  beautiful  and 
serviceable  results  in  staining  are  achieved  by  the  three-color  method, 
employing  safranin,  gentian  violet,  and  orange  G,  made  by  Gru'bler  and 


Reagents  and  Processes.  389 

obtainable  in  this  country  from  dealers  in  microscope  supplies.     The 
stains  are  made  as  follows  :  — 

1 .  A  saturated  solution  of  safranin  in  95  %  alcohol,  diluted  with  an 
equal  bulk  of  distilled  water. 

2.  A  saturated  solution  of  gentian  violet  in  distilled  water. 

3.  A  saturated  solution  of  orange  G  in  distilled  water,  diluted  with 
5  times  its  bulk  of  distilled  water. 

The  safranin  and  gentian  violet  should  be  kept  ready  for  use  in 
covered  tumblers  or  Stender  dishes,  and  the  orange  in  a  drop  bottle. 
In  addition  to  the  stains  there  should  be  conveniently  at  hand  — 

4.  A  drop  bottle  containing  absolute  alcohol. 

5.  A  drop  bottle  containing  clove  oil. 

6.  A  tumbler  of  xylene. 

7.  A  tumbler  of  95  %  alcohol  acidulated  with  i  drop  of  concentrated 
hydrochloric  acid. 

Proceed  with  the  staining  as  follows  :  — 

1.  Set  the  slide  upright  in  the  dish  of  safranin  for  a  few   hours 
or  over  night.     (The  paraffin  having  been  dissolved  away  in  xylene, 
and  the  latter  having  been  rinsed  off  in  a  dish  of  95  %  alcohol.) 

2.  Rinse  the  slide  quickly  in  water  and  place  it  in  the  dish  of  acidu- 
lated alcohol  (No.  7  above)  until  the  safranin  ceases  to  come  away  in 
clouds.     The  sections  should  appear  almost  decolorized. 

3.  Place  the  slide  in  the  dish  of  gentian  violet  for  10  minutes. 

4.  Rinse  off  the  gentian  violet  quickly  with  water  and  flood  the  sec- 
tions with  orange  G  from  the  drop  bottle  for  4  seconds. 

5.  Rinse  off  the  orange  with  water,  and  thoroughly  dehydrate  by 
holding  the  slide  slanting,  sections  upward,  and  dropping  absolute  alco- 
hol over  the  sections  from  the  drop  bottle. 

6.  Set  the  slide  in  a  horizontal  position  and  drop  clove  oil  from  the 
drop  bottle  over  the  sections.     The  preparation  should  now  be  watched 
under  low  power  of  the  microscope,  and  when  the  gentian  violet  has  lost 
its  too  great  intensity  and  has  a  transparent  quality,  drain  off  the  clove 
oil  and  set  the  slide  in  the  dish  of  xylene  and  let  it  remain  there  until 
ready  to  seal  the  mount  in  balsam.     If  the  sections  have  been  success- 
fully stained,  the  cytoplasm  will  be  stained  from  gray  to  orange,  the 
resting  nucleus  violet,  the  nucleolus  red.     In  the  dividing  nucleus  the 
chromosomes  will  be  red  and  the  spindle  fibers  violet.     Cutinized  mem- 
branes will  be  red,  lignified  membranes  blue,  and  cellulose  membranes 
will  be  almost  colorless. 


390  Introduction  to  Botany. 

To  seal  the  preparation  in  Canada  balsam,  remove  the  slide  from  the 
dish  of  xylene  and  place  it  in  a  horizontal  position.  Place  a  small  drop 
of  balsam  to  the  left  end  of  the  group  of  sections.  Grasp  a  thoroughly 
clean  and  dry  coverglass  between  the  thumb  and  forefinger  of  the  left 
hand.  Rest  the  lower  edge  of  the  coverglass  on  the  slide  close  to  the 
drop  of  balsam,  and  lower  it  to  the  right  over  the  sections.  Support 
the  upper  end  of  the  coverglass  by  means  of  a  dissecting  needle  held 
in  the  right  hand,  and  let  the  coverglass  down  slowly,  so  as  to  drive 
all  air  bubbles  forward  and  out  from  under  it.  During  this  process 
keep  the  coverglass  from  sliding  toward  the  left  by  means  of  a  needle. 
If  the  coverglass  is  of  the  oblong  or  square  form  it  is  often  needful, 
when  it  has  nearly  reached  the  horizontal  position,  to  grasp  its  edges 
by  means  of  the  thumb  and  middle  finger  of  the  left  hand  and  press 
it  down  against  the  slide  with  the  tip  of  the  forefinger,  with  a  sliding 
movement  from  the  left  toward  the  right  end  of  the  coverglass.  In  this 
way  the  balsam,  if  scantily  put  on,  is  forced  to  the  extreme  edge  of  the 
coverglass. 

The  slide  should  now  be  kept  at  about  52°  C.  for  several  days  to 
harden  the  balsam. 


PART   III. 


GLOSSARY. 


205  2°6  207 

FIGS.  205-213.    FORMS  .OF  UNDERGROUND  STEMS. 
205,  tubers  of  potato ;  206,  thick  rhizome  of  Iris ;  207,  upright  rhizome  of  violet ; 


208,  running  rhizome  of  goldenrod ;  209,  corm  of  Trillium ;  210,  longitudinal  sec- 
tion of  a  corm  or  solid  bulb ; 


211,  runner  or  stolon  of  strawberry;  212,  scaly  bulb  of  tiger  lily;  213,  tunicated 
bulb  of  onion. 


214 


215  216  217 

FIGS.  214-218.    FORMS  OF  ROOTS. 


218 


214,  fibrous  roots;  215,  conical  root;  216,  napiform  root;  217,  tuberous  roots,  the 

individual  roots  fusiform  ;  218,  nbro-tuberous  roots. 

392 


219   220       221         222,        223  224  225         226 

FIGS.  219-228.    FORMS  OF  LEAVES. 

219,  linear;  220,  lanceolate  ;  221,  oblong;  222,  elliptical ;  223,  ovate  ;  224,  cune- 
ate;  225,  orbicular;  226,  oblanceolate ;  227,  renitorm  or  kidney-shaped; 
228,  spatulate. 


227 


228 


236 


229    230    231   232  233  234 

FIGS.  229-239.    LEAF  MARGINS. 

229,  serrate;  230,  dentate ;  231,  crenate-serrate.  The  divisions  would  be  called 
crenate  when  rounded,  with  apices  pointing  outward  instead  of  upward.  232,  undu- 
late ;  233,  sinuate ;  234,  pinnately  lobed  or  incised ;  235,  more  deeply  pinnately 
lobed,  or  parted;  236,  pinnately  divided;  237,  palmately  lobed;  238,  palmately 
parted ;  239,  palmately  divided. 


237 


238 


239 


240 


242 


FIGS.  240-246.    BASES  OF  LEAVES. 
240,  cordate;  241,  hastate  or  halberd-shaped;  242,  auriculate; 


243  244  245  246 

243,  sagittate;  244,  perfoliate ;  245,  connate-perfoliate;  246,  peltate. 

393 


247          24°  249  25°  251  252  253  254 

FIGS.  247-254.    APICES  OF  LEAVES. 

247,  acuminate;    248,   acute;     249,  obtuse;     250,  mucronate;     251,  cuspidate; 
252,  truncate ;  253,  retuse ;  254,  emarginate. 


256  257 

FIGS.  255-260.    COMPOUND  LEAVES. 


258 


255,  oddly  pinnately  compound ;  256,  abruptly  pinnately  compound ;  257,  bipin- 
nately  compound;  258,  ternately  decompound  (the  two  primary  divisions  on  the 
right  are  similar  to  the  completed  one  on  the  left) ; 


259 


260 


259,  palmately  trifoliate  ;  260,  palmately  five  foliate  ;  261,  a  phyllodium,  the 
petiole  expanded  in  the  form  of  a  leaf;  262,  the  parts  of  a  leaf:  a,  the  blade; 
b,  the  petiole ;  c,  the  stipules  ; 


263  264  265 

263,  equitant  leaves  of  Iris;  264,  i,  stipules  adherent  to  the  base  of  the  petiole; 

264,  2,  stipules  clasping  the  stem  and  forming  an  ocrea;  265,  leaf-like  stipules. 

394 


267  268 

FIGS.  266-282.    FORMS  OF  COROLLAS. 

266,  papilionaceous :  s,  the  standard  (in  the  sense  of  flag  or  pennant)  ;  w,  the 
wings;  k,  the  carina  or  keel;  267,  a  papilionaceous  flower  seen  from  the  under 
side,  lettering  as  in  266 ;  268,  longitudinal  diagram  of  the  inflorescence  of  one  of  the 
Compositae:  /,  bract  of  involucre;  g,  ligulate  ray  flower;  r,  tubular  disk  flower; 


270 


271 


272 


273  274 

269,  trumpet-shaped ;  270,  funnel-form ;  271,  campanulate ;  272,  parts  of  a  petal 
y,  the  limb ;  z,  the  claw ;  273,  salver-shaped ;  274,  rotate ; 


281 


282 


278  279 

275,  bilabiate-personate ;  276,  bilabiate;  277,  inflated-tubular  corolla  of  Pentste- 
mon  split  open  and  showing  the  sterile  filament  between  the  four  fertile  ones; 
278,  flower  of  evening  primrose  with  inferior  ovary  and  so-called  calyx  tube  pro- 
longed above  it;  279,  tubular-rotate;  280,  rotate-funnel-form;  281,  bilabiate,  with 
helmeted  calyx ;  282,  trumpet-salver-form. 

395 


284  285  286  287 

FIGS.  283-287.    ^ESTIVATION  OF  THE  PETALS. 
283,  valvate;  284,  induplicate ;  285,  involute ;  286,  imbricate ;  287,  convolute. 


290 


291 


292293      294        295         296    297 


FIGS.  288-297.    PERTAINING  TO  STAMENS. 

288,  syngenesious,  united  by  the  anthers ;  289,  gynandrous,  united  to  the  pistil ; 
290,  monadelphous,  united  by  the  filaments;  291,  diadelphous,  united  in  two  sets; 
292,  anther  innate ;  293,  anther  adnate;  294,  anther  versatile ;  295,  anther  dehiscing 
by  longitudinal  slits ;  296,  anther  dehiscing  by  terminal  chinks  or  pores ;  297,  anther 
dehiscing  by  uplifted  valves. 


298 


300 


301 


302 


303 


FIGS.  298-308.    PERTAINING  TO  OVULES. 

298,  orthotropous  ovule;  299,  amphitropous  ovule;  300,  anatropous  ovule; 
301,  campylotropous  ovule;  302,  ovules  on  central  or  axial  placentae;  303,  ovules 
on  parietal  placentae,  pistil  compound ; 


304 

304,  ovules  on  parietal  placenta,  pistil  simple ;  305,  ovules  on  a  free  central  or  axial 
placenta;  306,  ovule  suspended ;  307,  ovule  erect ;  308,  ovule  ascending. 

396 


3°9  3IQ  311        312 

FIGS.  309-340.    PERTAINING  TO  FRUITS. 

309,  silique;   310,   sillicle;   311,  one  carpel  of  310  removed,  showing  ovules; 
312,  follicle;  313,  legume;  314,  loment;  315,  achene,  with  persistent  plumose  style; 


316  317  318  319.  320 

316,  achene  with  hairy  pappus  (calyx)  borne  on  a  long  beak;  317,  achene  with 
capillary  pappus ;  318,  achene  with  pappus  in  the  form  of  scales ;  319,  samara, 
winged  all  around ;  320,  double  samara  of  maple ; 


321  322  323  324  325  326 

321,  septicidal  dehiscence;  322,  loculicidal  dehiscence;  323,  septifragal  dehis- 
cence;  324,  another  mode  of  septifragal  dehiscence;  325,  circumscissile  dehis- 
cence ;  326,  utricle ; 


327  328  329  330  331  332 

327,  multiple  fruit ;  328,  section  of  a  single  fruit  from  327 ;  329,  longitudinal  sec- 
tion of  an  accessory  fruit  (strawberry) ;  330,  longitudinal  section  of  an  aggregate 
fruit  (blackberry);  331,  a  single  stone  fruit  from  330;  332,  longitudinal  section 
of  a  drupe  (peach)  ; 

397 


333 


334 


336 


333.  longitudinal  section  of  a  pome  (apple)  ;  334,  nut  of  the  acorn  type ;  335,  re- 
ceptacle and  nuts  of  the  water  lily ;  336,  a  berry ; 


337 


340 


337,  cross  section  of  a  berry  (cranberry) ;  338,  cross  section  of  a  pepo  or  gourd- 
fruit  ;  339,  longitudinal  section  of  a  syconium  or  fig-fruit ;  340,  an  ovule-bearing 
scale  of  the  pine  with  one  ripened  ovule  or  seed  in  position,  the  other  seed  removed 
and  shown  by  itself  on  the  right. 


398 


GLOSSARY. 

In  giving  the  derivation  of  words  in  the  Glossary,  the  abbreviation  L.  signifies  that  the 
root  word  is  Latin,  and  Gr.  that  it  is  Greek;  pr.  =  pronounced;  pi.  =  plural. 

Acaulesc'ent  (Gr.  a,  without;  L.  caulis,  a  stem):  with  little  or  no  apparent 

stem  above  ground. 
Acces'sory  fruit  (L.  accessus,  an  accession  or  increase) :  a  fruit  having  the 

receptacle  or  other  parts  as  an  important  part  of  the  whole,  as  in  the 

strawberry.     Fig.  329. 
Accumb'ent  (L.  accumbere,  to  lie  down  or  recline)  :  applied  to  cotyledons  in 

the  seed  when  lying  against  the  hypocotyl. 
Achene',  pr.  a-ken'  (Gr.  a,  without  or  not;  chainein,  to  gape  open)  :  a  small, 

dry  and  hard,  indehiscent,  one-seeded  fruit  consisting  of  a  single  carpel. 

Figs.  316-318. 

Achlamyd'eous  (Gr.  a,  without;  chtamys,  a  cloak)  :  without  calyx  and  corolla. 
Acic'ular  (L.  acicula,  diminutive  of  acus,  needle)  :  slender  or  needle-shaped. 
Acu'leate  (L.  aculeus,  a  sting  or  prickle)  :  prickly,  as  the  stem  of  the  rose. 
Acu'leolate :  somewhat  prickly. 
Acu'minate  (L.  acuminare,  to   sharpen)  :    gradually  tapering  to   a   point. 

Fig.  247. 

Acute'  (L.  acutus,  sharpened)  :  sharply,  but  rather  abruptly  pointed.    Fig.  248. 
Ad'nate  (L.  adnascor,  to  grow  to):    united  or  growing  together  —  applied 

only  to  the  union  of  unlike  parts,  as  of  stamens  to  petals.     When  the 

term  is  applied  to  anthers,  it  signifies  that  they  are  attached   for  their 

whole  length  to  the  inner  or  outer  face  of  the  filaments.     Fig.  293. 
Adventi'tious  (L.  adventicius,  unusual)  :  out  of  the  usual  place  —  applied  to 

buds  and  roots. 
JEstiva'tion  (L.  cestivare,  to  spend  or  pass  the  summer)  :  the  arrangement 

of  the  parts  of  the  flower  in  the  bud.     Figs.  283-287. 
Aggregate  fruit  (L.  ad '  +  gregario,  to  collect  into  a  flock  or  herd,  iiomgrex, 

a  flock  or  herd)  :  a  fruit  having  the  carpels  assembled  over  a  common 

receptacle,  as  in  the  blackberry.     Fig.  330. 
A'late,  pr.  a'late  (L.  a/a,  a  wing)  :  winged,  or  having  a  thin  expansion  like 

the  fruit  of  an  elm.     Fig.  319. 

Albu'men  (L.  albus,  white)  :  reserve  food  materials  stored  in  a  seed. 
Albu' ruinous  :  having  albumen. 

-399 


400  Introduction  to  Botany. 

Allia'ceous  (L.  allium,  garlic)  :  smelling  like  garlic  or  onions. 

Al'veolate  (L.  alveolus,  a  hollow  or  cavity)  :  pitted  so  as  to  appear  somewhat 

like  a  honeycomb. 

Am'ent  (L.  amentum,  thong  or  strap)  :  a  bracted  unisexual  spike. 
Amphit'ropous  (Gr.  amphi,  around ;    trope,  a  turn)  :   applied  to  ovules  or 

seeds  which  are  half  inverted,  with  the  point  of  attachment  near  the 

middle  of  one  side.     Fig.  299. 
Amplex'icaul  (L.  amplecti,  to  encircle ;   caulis,  a  stem)  :  applied  to  petioles 

or  stipules  encircling  the  stem.     Fig.  264,  2. 
Anat'ropous  (Gr.  ana,  up ;   trope,  a  turn)  :   having  the  ovule  inverted  as 

shown  in  Fig.  300. 
Androg'ynous  (Gr.  aner,  andros,  man ;   gyne,  woman)  :    having  staminate 

and  pistillate  flowers  on  the  same  inflorescence. 

An'giosperm  (Gr.  aggeion,  vessel ;  sperma,  seed)  :    plant  having  seeds  in- 
closed in  an  ovary. 
An'nual :  enduring  for  a  year.     Annual  ring :  that  portion  of  the  wood  of 

stem  or  root  produced  by  one  year's  growth.     Fig.  49. 
An'nular  (L.  annulus,  a  ring)  :  disposed  in  a  circle. 
An'ther  (Gr.  antheros,  flowery)  :  that  portion  of  the  stamen  containing  the 

pollen.     Fig.  87. 
Antherid'ium  (the  Greek  diminutive  ending  idion  +  anther)  :  the  organ  of 

cryptogams  which  produces  the  sperms.     Figs.  151  and  156. 
Antherozo'id  (Gr.  zoon,  animal ;  eidos,  resemblance  +  anther)  :  motile  sperms 

produced  in  some  cryptogams  and  in  Cycads.    Fig.  156.    Same  as  Sperm. 
Anthe'sis  (Gr.  anthesis,  flowering)  :  the  time  or  condition  of  expansion  of 

the  flower. 

Apet'alous  (Gr.  a,  without ;  petalon,  a  leaf)  :  without  petals. 
Apic'ulate  (L.  apiculum,  a  little  point)  :   ending  in  a  short,  sharp,  but  not 

hard  point. 

Appressed' :  close  and  flat  against. 

Arach/noid  (Gr.  arachne,  spider,  or  spider's  web  ;   eidos,  resemblance)  :  cob- 
webby. 
Archego'nium  (Gr.  arche,  beginning ;  gone,  race)  :  the  organ  of  cryptogams 

and  gymnosperms  which  produces  the  eggs.  Figs.  151  and  156. 
Are'olate  (L.  areola,  diminutive  of  area)  :  divided  into  small  spaces. 
Ar/il :  an  expansion  arising  from  the  base  of  a  seed  and  enveloping  it,  as  in 

the  seed  of  the  white  water  lily.     Ar'illate  :  having  an  aril. 
Ascend'ing  :  rising  obliquely.     Ascending  ovule  :  ascending  from  just  above 

the  base  of  the  ovary.     Fig.  308. 
Asexual  spore :  a  spore  produced  by  the  division  of  a  mother  cell  without 

previous  cell  union. 


Glossary.  401 

Aur'icle  (L.  auricule,  diminutive  of  auris,  ear)  :  an  ear-shaped  appendage. 

Fig.  242. 

Auric 'ulate  :  provided  with  auricles. 
Awn:  a  bristle-like  appendage. 
Ax'il  (L.  axilla,  armpit)  :  the  angle  formed  between  the  axis  of  a  stem  and 

any  part  arising  from  it.     Ax'illary :  situated  in  an  axil. 
Ax'is  (L.  axis,  axle)  :  the  central  line  of  an  organ. 

Barbed  (L.  barba,  beard)  :  provided  with  rigid  points  or  bristles,  usually 
reflexed.  Bar'bellate :  finely  barbed. 

Bar'bulate :  finely  bearded. 

Bast :  the  fibrous  part  of  the  bark. 

Bearded :  awned,  as  spikes  of  wheat ;  or  having  tufts  of  hairs. 

Berry :  a  fleshy  or  pulpy  fruit,  such  as  a  gooseberry,  grape,  tomato,  cranberry, 
etc.  Fig.  337. 

Bi-,  bis- :  Latin,  in  compound  words  signifying  twice. 

Bident'ate  (L.  dens,  a  tooth)  :  having  two  teeth. 

Bien'nial  {bi-  +  L.  annus,  a  year)  :  a  plant  which  requires  two  years  to  com- 
plete its  life  cycle ;  usually  flowering  and  fruiting  the  second  year  only, 
and  then  dying. 

Bi'fid  (L.  hi-  -\-findere,  to  cut)  :  two-cleft. 

Bila'biate  (L.  bi-  +  labium,  a  lip)  :  divided  into  two  lips.    Figs.  275  and  276. 

Biloc'ular  (L.  bi-  +  loculus,  a  compartment)  :  two-celled. 

Bipin'nate  (L.  bi-  +  pinnatus,  feathered  ;  pinna,  a  feather)  :  having  both 
primary  and  secondary  divisions  of  a  compound  leaf  pinnate.  See  Pin- 
nate. Figs.  255-257. 

Bladdery :  thin  and  inflated. 

Blade  :  the  expanded  portion  of  a  leaf.     Fig.  262,  a. 

Bract  (L.  bractea,  a  thin  plate)  :  a  modified  or  reduced  leaf  subtending  a 
flower,  or  belonging  to  an  inflorescence.  Fig.  268,  /. 

Bract'eate  :  provided  with  bracts. 

Bract'eose  :  having  numerous  or  conspicuous  bracts. 

Bract'let :  a  secondary  bract,  occurring  on  the  pedicel  of  a  flower  instead  of 
subtending  it.  Bract'eolate  :  having  bractlets. 

Bulb  (L.  bulbus,  a  bulb)  :  a  subterranean  bud  with  fleshy  scales  or  coats. 
Figs.  212  and  213. 

Bulbif  'erous  (bulb  +  L.  fero,  I  bear)  :  bearing  bulbs. 

Bulb'let :  a  small  bulb,  usually  one  borne  above  ground  on  the  stem. 

Bulbous  :  having  the  character  of  a  bulb. 

Cadu'cous  (L.  cadricus,  falling)  :  falling  off  very  early;  applied  to  petals  which 
fall  as  the  flower  opens. 


402  Introduction  to  Botany. 

Cal'lus  (L.  callosus,  hard)  :  a  hard  protuberance;  or  the  hardened  coating 
which  forms  over  the  end  of  a  cutting  which  has  been  inserted  in  the  soil. 

Calyp'tra  (Gr.  calyptra,  a  veil)  :  the  membranous  covering  over  the  capsule 
of  a  moss,  formed  from  the  apex  of  the  archegonium.  Fig.  150,  c. 

Ca'lyx  (Gr.  calyx,  a  cup)  :  the  outer  whorl  of  floral  envelopes.     Fig.  87. 

Campan'ulate  (L.  campana,  a  bell)  :  bell-shaped.     Fig.  271. 

Campylot'ropous  (Gr.  campylos,  curved;  trope,  a  turn)  :  applied  to  an  ovule 
which  has  curved  so  that  the  micropyle  is  about  on  a  plane  with  the 
hilum.  Fig.  301. 

Canalic'ulate  (L.  canalis,  a  canal  or  channel)  :  longitudinally  grooved. 

Canes'cent  (L.  canescens,  growing  gray)  :  hoary  from  a  gray  pubescence. 

Cap'itate  (L.  caput,  the  head)  :  head-shaped,  or  collected  into  a  head. 
Fig.  82,  /  and  u. 

Cap'sule  (L.  capsula,  a  small  box)  :  the  spore-case  of  mosses;  a  dry  fruit  of 
more  than  one  carpel,  which  opens  to  discharge  its  seeds.  Figs.  321-324. 

Car'inate  (L.  carina,  a  keel)  :  having  a  median  longitudinal  projection  on  the 
lower  surface. 

Car'pel  (Gr.  carpos,  fruit)  :  a  simple  pistil,  or  a  single  element  of  a  compound 
pistil;  a  single  female  sporophyll. 

Car'uncle  (L.  taruncnla,  diminutive  of  caro,  flesh)  :  a  wart  or  protuberance 
near  the  hilum  of  a  seed,  as  in  seed  of  castor  bean. 

Caryop'sis  (Gr.  karyon,  nut;  opsisf  resemblance)  :  a  seed-like  fruit  with  the 
capsule  closely  adherent  to  the  seed,  as  in  corn  and  other  grasses. 

Cat 'kin :  same  as  Ament. 

Caud'ate  (L.  cauda,  a  tail)  :  having  a  tail-like  appendage. 

Cau'dex  (L.  caudex,  stem  or  trunk)  :  the  main  axis  of  a  plant;  also  the  per- 
ennial rootstock  of  an  otherwise  annual  plant.  Figs.  206  and  207. 

Caules'cent  (L.  caulis,  stalk  or  stem)  :  having  an  apparent  stem  above  ground. 

Cau'line,  pr.  kaw'lin  or  kaw'line :  belonging  to  the  stem. 

Ces'pitose  (L.  cespes,  turf)  :  matted,  or  growing  in  tufts. 

Chaff :  a  dry  or  membranous  scale  or  bract. 

Charta'ceous  (L.  charta,  paper)  :  having  a  papery  texture. 

Chlo'rophyll  (Gr.  chloros,  grass-green;  phyllon,  a  leaf)  :  the  green  coloring 
matter  of  plants. 

Chlo'roplast  (Gr.  chloros  +  plastos,  molded)  :  the  plastid  or  grain  of  proto- 
plasm which  contains  the  chlorophyll.  Fig.  36. 

Chro'moplast  (Gr.  chroma,  color  +  plastos}  :  plastid  containing  other  color- 
ing matter  than  chlorophyll. 

Chro'mosome  (Gr.  chroma  +  soma,  a  body)  :  one  of  the  strongly  staining 
bodies  of  definite  number  into  which  the  body  of  the  nucleus  divides 
in  nuclear  division.  Fig.  46. 


Glossary.  403 

Cil'iate  (L.  cilium,  eyelid)  :  fringed  with  hairs. 

Cil'iolate :  fringed  with  minute  hairs. 

Cine'reous  (L.  cinis,  cineris,  ashes)  :  ashen  or  grayish. 

Cir'cinnate  (L.  cirdnare,  to  make  round)  :  coiled  downward  from  the  tip. 

Sometimes  spelled  with  one  n. 
Circumscis'sile  (L.  circum,  around;  scindo,  scissus,  to  split)  :    dehiscing  by 

transverse  circular  cleavage.     Fig.  325. 

Cla'vate  (L.  clava,  a  club)  :  club-shaped;   thickening  toward  the  apex. 
Claw :  the  narrowed  base  of  certain  petals.     Fig.  272,  z. 
Cleft :  split  nearly  to  the  middle.     Fig.  235. 
Cleistog'amous  (Gr.  kleistos,  shut  or  closed;  games,  marriage)  :    applied  to 

flowers  which  do  not  open,  but  become  self-fertilized  in  the  bud. 
Coales'cent  (L.  coalesco,  to  grow  together)  :  having  organs  of  the  same  kind 

grown  together. 

Coated :  applied  to  bulbs,  such  as  the  onion,  having  inwrapping  scales. 
Coch'leate  (L.  cochlea,  snail  or  snail  shell)  :  spirally  coiled. 
Cohe'rent  (L.  cohaereo,  to  cling  to)  :  applied  to  organs  of  the  same  kind  which 

are  united,  as  in  the  union  of  the  petals  to  form  a  gamopetalous  corolla. 
COm'missure  (L.  commissura,  a  joining  together)  :  the  face  along  which  one 

carpel  joins  another,  as  in  the  Umbelliferae. 
Co'mose  (L.  comosus,  hairy)  :  having  a  tuft  of  hair. 
Com'plicate :  folded  upon  itself. 
Com'pound:    consisting  of  two  or  more  united  similar  parts.     Compound 

ovary :  consisting  of  two  or  more  united  carpels. 
Compressed' :  flattened  laterally. 
Condu'plicate :  folded  together  lengthwise. 

Cone :  fruit  of  the  pine,  etc.,  with  ovule-bearing  scales.     Figs.  93  and  94. 
Con/fluent :  blended  into  one. 

Con'ical  (Gr.  konos,  a  cone)  :  round  and  tapering  to  a  point.     Fig.  215. 
Coniferous  (Gr.  konos,  a  cone;   'L.ferre,  to  bear)  :  cone-bearing. 
Con'nate  (L.  con-,  with,  together;    natus,  born)  :   united,  particularly  at  the 

base.     Connate-perfoliate :    applied  to  leaves  which  are  united  at  the 

base  around  the  stem.     Fig.  245. 
Connective :    portion  of  the  filament  which  connects  the  two  lobes  of  an 

anther.     Fig.  292. 

Conni'vent :  converging  or  coming  into  contact. 
Con 'volute  :  rolled  up  longitudinally. 
Cor'date  (L.  cor,  heart)  :  heart-shaped,  with  the  point  remote  from  the  place 

of  attachment.     Fig.  240. 
Corm  (Gr.  kormos,  a  trimmed  tree  trunk)  :  a  solid  bulb-like  expansion  at  the 

base  of  some  stems  below  ground.     Figs.  209  and  210. 


404  Introduction  to  Botany. 

Corol'la  (L.  corolla,  diminutive  of  corona,  a  crown  or  garland)  :  the  inner 
whorl  of  the  floral  envelope,  that  is,  the  petals  taken  collectively,  whether 
distinct  or  united.  Fig.  87. 

Coro'niform  (L.  corona,  a  crown;  forma,  form)  :  shaped  like  a  crown. 

Cor'ymb  (L.  corymbus,  a  cluster  of  flowers  or  fruit)  :  a  flat-topped  or  merely 
convex  cluster  of  flowers  whose  pedicels  arise  at  different  heights  on  the 
main  axis,  the  older  flowers  being  outermost.  Fig.  83,  x. 

Cor'ymbose :  in  corymbs,  or  corymb-like. 

Cos'tate  (L.  costa,  a  rib)  :  having  one  or  more  longitudinal  primary  ribs. 

Cotyle'dons  (Gr.  kotyledon,  any  cup-shaped  hollow  or  cavity)  :  the  first  leaves 
of  an  embryo. 

Creeping:   running  along  or  over  the  ground  and  rooting.     Fig.  211. 

Cre'nate  (L.  crena,  a  notch)  :  having  margins  with  rounded  teeth.    Fig.  231. 

Cren'ulate :  finely  crenate. 

Crusta'ceous  (L.  crusta,  a  crust)  :  hard  and  brittle. 

Cryp'togam  (Gr.  kryptos,  hidden;  gamos,  marriage)  :  plant  without  flowers 
in  the  usual  sense,  and  without  true  seeds,  such  as  the  ferns,  mosses,  and 
lower  plants. 

Cu'cullate,  pr.  ku'kull-ate  (L.  cucullus,  cap  or  hood)  :  hooded  or  hood- 
shaped. 

Culm  (L.  culmus,  stalk  or  stem,  especially  of  cereals)  :  the  hollow  stem  of 
grasses. 

Cu'neate  (L.  cuneus,  a  wedge)  :  wedge-shaped.     Fig.  224. 

Cus'pidate  (L.  cuspis,  a  point)  :  terminating  in  a  hard  and  sharp  point. 
Fig.  251. 

Cylindra'ceous  (Gr.  kylindros,  a  roller)  :  somewhat  cylindrical. 

Cyme  (Gr.  kyma,  anything  swollen,  a  wave  or  billow) :  a  flat  or  convex 
flower  cluster  similar  to  a  corymb,  but  having  the  innermost  flowers 
oldest.  Fig.  82,  v.  Cy'mose  :  cyme-like,  or  bearing  cymes. 

Cy'toplasm  (Gr.  kytos,  a  hollow  vessel;  plasma,  anything  formed  or  molded)  : 
the  general  protoplasm  of  the  cell  exclusive  of  nucleus  and  plastids. 

Decid'uOUS  (L.  decidere,  to  fall  down)  :  falling  off;   not  evergreen. 

Decom'pound :  more  than  once  compound  or  divided.     Figs.  257  and  258. 

Decum'bent  (L.  decumbens,  reclining)  :  reclining  as  if  too  weak  to  stand,  and 
tending  to  rise  at  the  apex. 

Decur'rent  (L.  decurrens,  running  down)  :  applied  to  a  leaf  whose  base  ex- 
tends downward  below  the  insertion  and  forms  a  sort  of  wing  along  the 
stem. 

Decurved' :  curved  downward. 

Deflexed' :  curved  or  bent  abruptly  downward. 


Glossary.  405 


Dehis'cence :  definite  mode  of  opening  of  capsules  and  anthers.  Figs.  295- 
297  and  321-326. 

Dehis'cent  (L.  dehiscere,  to  yawn)  :  splitting  open  in  a  definite  way. 

Del'toid :  shaped  like  the  Greek  letter  A  (delta). 

Den'tate  (L.  dens,  a  tooth)  :  toothed,  usually  with  the  teeth  directed  out- 
ward. Fig.  230.  Dentic'ulate  :  minutely  dentate. 

Depau'perate  (L.  depauperatus,  impoverished)  :  much  reduced  in  size. 

Depressed' :  somewhat  flattened  from  above. 

Determinate :  applied  to  the  growth  of  stems  where  increase  in  length  is 
terminated  by  a  winter  bud;  applied  to  inflorescences  where  flowering 
begins  with  a  terminal  or  inner  bud,  as  in  cymes.  Fig.  82,  v. 

Di-,  dis- :  Greek  prefix  signifying  two  or  twice. 

Diadel'phous  (Gr.  di-  +  adelphos,  brother)  :  said  of  stamens  when  combined 
in  two  sets.  Fig.  291. 

Dian'drous  (Gr.  di-  -f  finer,  andros,  man)  :  having  two  stamens. 

Dicarp'ellary  (Gr.  di-  +  karpos,  fruit)  :  composed  of  two  carpels. 

Dichog'amy  (Gr.  dicha,  asunder;  gamos,  marriage)  :  the  condition  of  flowers 
whose  stamens  and  pistil  do  not  mature  simultaneously,  preventing  self- 
fertilization. 

Dichot'omous  (Gr.  dicha  -f  temnein,  to  cut)  :  forking  regularly  in  pairs. 

Dicotyle'don :  a  plant  having  two  cotyledons. 

Did'ymous  (Gr.  didymos,  twin)  :  occurring  in  pairs. 

Didyn'amous  (Gr.  di-  +  dynamis,  power)  :  applied  to  stamens  when  in  two 
pairs  of  unequal  length. 

Diffuse' :  widely  or  loosely  spreading. 

Dig'itate  (L.  digitus,  a  finger)  :  applied  to  a  compound  leaf  whose  leaflets 
are  all  borne  at  the  apex  of  the  petiole.  Figs.  259  and  260. 

Digitately :  applied  to  leaves  which  are  lobed,  cleft,  parted,  or  divided  in 
digitate  manner,  as  in  Figs.  237-239. 

Dim/erous  (Gr.  di-  +  meros,  a  part)  :  applied  to  a  flower  having  all  of  its 
parts  in  twos. 

Dimor'phous  (Gr.  di-  +  morphe,  form)  :  occurring  in  two  forms.     Fig.  91. 

Dice'cious,  pr.  di-e'shus  (Gr.  di-  +  oikos,  a  house)  :  having  only  unisexual 
flowers,  the  staminate  and  pistillate  flowers  being  borne  on  different 
individuals. 

Dis'coid  (Gr.  diskos,  a  round  plate;  eidos,  form)  :  resembling  a  disk;  applied 
to  the  heads  of  Composite  which  are  composed  of  disk  flowers  only. 

Disk :  the  central  part  of  the  head  of  Composite  as  opposed  to  the  margin. 

Dissect'ed-:  deeply  cut  into  many  divisions. 

Dissep'iment  (dis-  +  L.  salpire,  to  inclose)  :  the  separating  membrane  or 
wall  in  a  compound  ovary  or  fruit. 


406  Introduction  to   Botany. 

Dis'tichous  (di-  -f  Gr.  stichos,  a  row  or  verse)  :  in  two  vertical  rows. 

Distinct' :  separate,  not  united. 

Divar'icate  (di-  +  L.  varicare,  to  straddle)  :  widely  diverging. 

Diver'gent :  inclined  away  from  each  other. 

Divi'ded :  lobed  or  segmented  to  the  base  or  midrib.     Figs.  236  and  239. 

Dor'sal  (L.  dorsum,  the  back)  :  the  surface  of  a  member  turned  away  from 

the  main  axis;   thus,  the  dorsal  surface  of  a  leaf  is  its  under  surface. 
Drupa'ceous :  producing  or  having  the  form  of  a  drupe. 
Drupe  (L.  drupa,  an  overripe  olive)  :  a  fleshy  or  pulpy  fruit  with  the  inner 

portion  hard  or  stony.     Figs.  331  and  332. 

E-  or  ex- :  in  compound  words  meaning  out  from,  without,  or  destitute  of. 

Ebe'neous :  black  as  ebony. 

Ebrac'teate :  without  bracts. 

Ech'inate,  pr.  ek'inate  (L.  echinus,  a  hedgehog)  :  beset  with  bristles;   like  a 

hedgehog. 

Effuse' :  very  loosely  spreading. 
Egg :  the  female  cell  which  after    fusion  with  the  sperm  develops  into  an 

embryo  or  new  plant. 
Ela'ter  (Gr.  elater,  a  driver)  :  a  spirally  marked  thread  borne  among  the 

spores  of  some  liverworts  and  slime  moulds. 

Ellipsoidal  (Gr.  elleipsis,  ellipse;   eidos,  form)  :  shaped  like  an  ellipse. 
Emar'ginate  :  having  a  decided  terminal  notch.     Fig.  254. 
Em'bryo  (Gr.  embryon,  an  embryo)  :  the  rudimentary  plant  within  a  seed. 
En'docarp   (Gr.  endon,  within;  karpos,  fruit)  :  the  inner  layer  of  a  matured 

ovary. 
En'dogen   (Gr.  endon  +  genos,  descent  or  birth)  :  a  plant  among  the  Sper- 

matophytes  without  a  true  cambium  ring,  as  in  grasses  and  monocotyled- 

onous  plants  in  general. 

Endogenous:  pertaining  to  an  endogen;  arising  from  deep-seated  tissues. 
Entire' :  with  undivided  margin. 
Ephem'eral  (Gr.  ephemeras,  daily;  from  epi,  over,  and  hemera,  day)  :  lasting 

only  one  day. 

Ep'icarp  (Gr.  epi,  upon  or  over;  carpos,  fruit)  :  outer  layer  of  a  mature  ovary. 
Epicot'yl    (Gr.   epi  +  cotyle,   hollow  vessel) :    the  young   shoot  above  the 

cotyledons. 
Epider'mis  (Gr.  epi  +  derma,  skin)  :  the  outer  protective  layer  of  cells  of 

leaves,  young  stems  and  roots,  and  fruits.     In  old  stems  and  roots  the 

epidermis  becomes  permanently  replaced  by  cork. 
Epig'ynous   (Gr.  epi  -f  gyne,  woman)  :  growing   from   the   summit   of  the 

ovary,  or  apparently  so.     Fig.  123,  C. 


Glossary.  407 

Ep'iphyte  (Gr.  epi  +  phyton,  plant):  a-  plant  which  grows  upon  other 
plants,  but  not  parasitically;  an  air  plant.  Fig.  16. 

Eq'uitant  (L.  equitare,  to  ride)  :  said  of  leaves  which  are  folded  longi- 
tudinally so  as  to  bestride  those  next  above  and  within,  as  in  Iris. 
Fig.  263. 

Erose' :   (L.  e,  out;  rodere,  to  gnaw)  :  irregularly  jagged  as  if  gnawed. 

Essential  organs  :  stamens  and  pistils. 

Evanes'cent  (L.  evanescere,  to  vanish)  :  of  short  duration. 

Ev'ergreen :  bearing  green  foliage  throughout  the  year. 

Exalbu'minous  (L.  ex,  without  +  albumen,  which  see)  :  said  of  seeds  having 
the  reserve  materials  stored  entirely  within  the  embryo,  as  in  Lima  bean. 

Excur'rent  (L.  ex,  out;  currens,  running):  applied  to  the  midrib  or  veins  of 
a  leaf  when  they  project  beyond  the  margin;  also  to  a  stem  or  trunk 
when  it  persists  as  the  main  axis  to  the  top.  Fig.  27. 

Exfo'liate  (L.  ex,  from;  folium,  leaf)  :  to  peel  off  in  scales  or  thin  layers. 

Ex'ogen  (Gr.  ex,  out;  genos,  descent  or  birth)  :  a  plant  with  a  true  cambium 
ring  which  adds  new  wood  to  the  outside  of  that  already  formed. 

Exog'enous :  belonging  to  the  exogens;  having  the  structure  of  an  exogen. 

Exsert'ed  (L.  exserere,  to  stretch  out  or  forth)  :  applied  to  stamens  which 
protrude  beyond  the  tube  of  the  corolla. 

Exstip'ulate  (L.ex,  in  the  privative  sense  of  without;  and  stipulate'} :  without 
stipules. 

Ex'tine,  pr.  ex'tin  or  ex'teen  (L.  exter,  on  the  outside)  :  the  outer  membrane 
of  a  pollen  grain. 

Extrorse'  (L.  extra,  on  the  outside;  versus,  toward):  facing  outward;  ap- 
plied to  anthers  which  occupy  the  outside  of  a  filament. 

Fal'cate  (L.falx,  sickle  or  scythe)  :  sickle-  or  scythe-shaped. 

Farina'ceous  (L,.  farina,  meal)  :  containing  starch;   starchy. 

Far'inose  :  covered  with  a  mealy  powder. 

Fas'cicle  (L.  fasciculus,  diminutive  of  fascis,  a  bundle)  :  a  close  bundle  or 
cluster  of  flowers,  leaves,  stems,  or  roots. 

Fastig'iate  (L.  fastigium,  gable  end  or  top) :  upright  and  parallel  in 
clusters. 

Fave'olate  (L.favus,  honeycomb)  :  honeycombed. 

Ferru'ginous  (L.  ferrugo,  iron  rust)  :  rust  color. 

Fer'tile  (L.  fertilis,  capable  of  producing  fruit)  :  applied  to  flowers  with  pis- 
tils, or  to  anthers  with  pollen. 

Fi'brillose  (L.  fibra,  a  small  fiber  or  filament)  :  covered  with  hair-like 
appendages. 

Fi'brous  :  containing  or  consisting  of  fibers. 


408  Introduction  to  Botany 

Fil'ament  (L.  filum,  thread)  :    the  usually  slender  stalk  which  supports  the 

anther;  any  thread-like  object  or  appendage. 
Filament'ous :  composed  of  filaments  or  threads. 
Fil'iform :  slender  and  thread-like. 

Fim'briate  (L.fimbria,  fringe) :  having  the  margin  beset  with  slender  processes. 
Fimbril'late :  minutely  fringed. 

Fis'tular  (L,  fistula,  a  pipe  or  reed)  :  hollow  and  cylindrical. 
Flac'cid,  pr.  flak'sid  (L.flaccus,  flabby)  :  weak  and  without  rigidity. 
Flex'uous  (L.flexus,  bent)  :  zigzag;  bent  alternately  from  side  to  side. 
Floccose'  (L.floccus,  a  flock  of  wool)  :  having  tufts  of  soft  hair. 
Floral-en 'velopes :  calyx  and  corolla. 

Folia'ceous  (L.  folium,  leaf)  :  having  the  shape  or  texture  of  a  leaf. 
Fo'liar:  leaf-like;  pertaining  to  a  leaf. 

Fo'liate :  provided  with  leaves;  bi-foliate,  two-leaved;  tri-foliate,  three-leaved. 
Fo'liolate  :  provided  with  leaflets. 
Fol'licle  (L.folliculum,  a  small  bag)  :    a  fruit  of  one  carpel  dehiscing  along 

the  ventral  suture,  to  which  the  seeds  are  attached.     Fig.  312. 
Follic'ular:  like  a  follicle. 
For'nicate  (L.  fornix,  a  vault)  :  having  scale-like  appendages  which  converge 

and  close  the  tube  of  the  corolla. 
Free :  not  adnate  to  other  organs. 
Frond  (L.frons,  a  leaf)  :  the  leaf  of  ferns  and  other  cryptogams,  or  the  shoot 

of  Lemancese  and  other  Spermatophytes  which  is  not  differentiated  into 

stem  and  leaf. 
Fruit:  the  ripened  ovary  and  its  contents;  or,  in  a  broader  sense,  the  ripened 

ovary  and  contents,  together  with  any  structures  which  by  adhesion  are 

an  integral  part  of  it. 

Fuga'ceous  (L.fugax,  fleeing)  :  soon  fading  or  falling  off. 
Ful'vous  (L.  fulvus}  :  dull  yellow  or  tawny. 
Fu'nicle  (L.  funiculus,  diminutive  of  funis,  a  cord)  :   the  little  stalk  which 

connects  the  ovule  or  seed  with  the  placenta. 
Fun'nelform :  applied  to  corollas  with  a  tube  gradually  enlarging  from  the 

base.     Fig.  270. 
Fu'siform  (L.  fusus,  a  spindle;  forma,  shape)  :    tapering  toward  each  end, 

spindle-shaped.     Fig.  217. 

Ga'lea  (L.  galea,  a  helmet)  :  the  helmet-shaped  upper  lip  of  labiate  flowers. 

Fig.  276.     Ga'leate:  helmet-shaped;  having  a  galea. 
Gam'etophyte  (Gr.  gametes,  a  spouse;  phyton,  plant)  :  the  generation  which 

bears  the  eggs  and  sperms,  and  gives  lise  to  the  sporophyte.     Figs.  157, 

158,  and  159. 


Glossary.  409 

Gamopet'alae  (Gr.  games,  marriage  or  union;  petalon,  a  flower  leaf)  :  plants 

having  the  petals  united. 

Gamopet'alous  :  having  the  petals  more  or  less  united. 
Gamoph'yllous  (Gr.  gamos  -f  phyllon,  a  leaf)  :  having  leaves  united  by  their 

edges. 
Gem/ma  (L.  gemma,  a  bud)  :    a  young  bud;   an  asexual  bud-like  body  of 

Hepaticse. 

Gemmip'arous  (L.  gemma  -\-parere,  to  produce)  :  bearing  gemmae. 
Gen'era :  plural  of  genus. 
Genic'ulate  (L.  geniculum,  little  knee,  or  joint,  diminutive  of  genu,  knee)  : 

-bent  abruptly  at  an  angle. 
Ge'nus  (L.  genus,  a  race)  :    the  smallest  natural  group  containing  distinct 

species. 
Geotrop'ic  (Gr.  ge,  the  earth;   trope,  a  turning)  :   relating  to  or  evincing  geo- 

tropism. 
Geot'ropism :    the  property  or  state  of  a  growing  member  or  organ  which 

enables  it  to  respond  to  gravity  as  a  guide  to  the  direction  which  it 

shall  take. 

GiVbous  (L.  gibbus,  humped)  :  swollen  or  humped  on  one  side. 
Gla'brate  (L.  glaber,  smooth)  :  nearly  smooth  or  becoming  smooth  with  age. 
Gla'brous :  smooth ;  without  hairs. 
Gland  (L.  glans,  an  acorn)  :   an  organ  of  secretion,  or  a  small  prominence 

apparently  having  a  secreting  function. 
Glan/dular :  bearing  glands,  or  of  the  nature  of  a  gland. 
Glau'cous,  pr.  glaw'kus  (Gr.  glaukos,  bluish  gray)  :  covered  with  a  bloom  or 

powder,  as  a  plum  or  cabbage  leaf. 

Glo'bose,  glob'ular  (L.  globus,  a  sphere)  :  spherical  or  nearly  so. 
Glochid'iate  (Gr.  glochis,  a  point  of  an  arrow)  :   having  barbs. 
Glom'erate  (L.  glomus,  a  ball)  :  collected  into  a  head,  or  compactly  clustered. 
Gluma'ceous :  resembling  or  provided  with  glumes. 
Glume  (L.  gluma,  hull  or  husk)  :   an  outer  husk  or  bract  on  the  spikelet  of 

grasses. 

Gran'ular  (L.  granum,  grain)  :  consisting  of  or  resembling  small  grains. 
Grega'rious  (L.  grex,  gregis,  a  herd)  :  growing  in  clusters* 
Gymnosper'mae   (Gr.  gymnos,  naked;    sperma,  seed)  :    plants  with  naked 

ovules,  as  the  conifers.     Fig.  94. 
Gymnosper'mous :  bearing  naked  ovules  and  seeds. 
"Gynae'cium  (Gr.  gynaikeion,  woman's  apartment,  from  gyne,  woman,  and 

oikion,  house)  :  the  pistil  or  pistils  of  a  flower  taken  collectively. 
Gynan'drous  (Gr.  gyne,  woman ;    aner,  andros,  man)  :    having  the  stamens 

borne  upon  the  pistil.     Fig.  289. 


410  Introduction  to  Botany. 

Gy'nobase  (Gr.  gyne  +  basis,  a  pedestal)  :  an  enlargement  or  prolongation  of 

the  receptacle  bearing  the  gynsecium. 
Gy'nophore  (Gr.gyne  +  phoreo,  I  carry):  a  more  or  less  elongated  pedicel 

carrying  the  pistil. 

Hab'it  (L.  habitus,  appearance)  :  the  general  appearance  of  a  plant. 
Hab'itat  (L.  habitatio,  dwelling)  :  the  kind  of  locality  in  which  a  plant  grows. 
Hal'berd-shaped :  same  as  hastate. 
Haloph'ilous  (Gr.  hals,  halos,  salt,  the  sea ;  philein,  to  love)  :  adapted  to  a 

salty  substratum. 

Hal'ophyte  (Gr.  halos  -f  phyton,  plant)  :  a  plant  abounding  in  salty  soils. 
Has'tate  (L.  hasta,  a  spear)  :  arrow-shaped,  with  the  basal  lobes  pointing 

outward  instead  of  downward.     Fig.  241. 
Hausto'rium  (L.  haurire,  haustum,  to  drink)  :    the  sucker-like  rootlet  of 

parasitic  plants,  as  of  the  dodder. 
Head:  a  dense  cluster  of   sessile   or  nearly  sessile  flowers  on  a  short  axis. 

Fig.  82,  /  and  «. 
Herb  (L.  herba,  herbage)  :  a  plant  without  a  persistent  woody  stem  above 

ground.     Herba'ceous :  having  the  characters  of  an  herb. 
Hermaph'rodite  (from  Hermaphroditus,  who,  in  mythical  story,  was  joined  in 

one   body   with   Salmacis)  :    having   stamens   and   pistils   in   the   same 

flower. 
Hesperid'ium  (Gr.  Hesperides,  names  of  mythological  characters  said  to  own 

a  garden  of  golden  apples)  :  a  berry  with  a  thick  but  not  hard  rind,  such 

as  the  orange  and  lemon. 
Hi'lum  (L.  hilum,  a  trifle  or  little  thing)  :  the  scar  or  place  of  attachment  of 

the  seed. 

Hir'sute  (L.  hirsutus,  hairy)  :  beset  with  rather  stiff  hairs. 
His'pid  (L.  hispidus,  bristly)  :  beset  with  stiff  hairs  or  bristles. 
Hoar'y :  grayish  from  a  fine  pubescence. 
Homog'amy  (Gr.  homos,  one  and  the  same  ;  games,  marriage)  :  simultaneous 

maturity  of  pollen  and  stigmas  in  a  perfect  flower. 
Homog'amous  :  bearing  but  one  kind  of  flowers. 
Hood'ed :  shaped  like  a  hood. 
Host :  a  plant  which  nourishes  a  parasite. 
Hy'aline  (Gr.  hyalines,  of  glass)  :  colorless,  translucent. 
Hy'brid  (L.  hybrida,  a  mongrel)  :  a  plant  produced  by  the  crossing  of  two 

species. 
Hy'drophyte  (Gr.  hydor,  water ;  phyton,  a  plant)  :  a  plant  adapted  to  an 

aquatic  or  moist  habitat. 
Hydrophyt'ic :  relating  to  hydrophytes. 


Glossary.  411 

Hy'pha  (Gr.  hyphe,  a  web)  :  one  of  the  thread-like  elements  of  the  body  of  a 

fungus. 
Hypocot'yl  (Gr.  hypo,  under ;  cotyle,  a  hollow)  :  the  axis  of  an  embryo  below 

the  cotyledons. 

Hypocotyle 'denary :  below  the  cotyledons  and  above  the  root. 
Hypog'ynous  (Gr.  hypo,  under ;  gyne,  woman)  :  inserted  beneath  the  pistil  or 

gynaecium  and  free  from  it.    Fig.  123,  A. 

Im'bricate  (L.  imbricatus,  covered  with  gutter  tiles)  :  overlapping  like  the 
shingles  on  a  roof.  Fig.  286. 

Immersed' :  growing  below  the  surface  of  water  ;  embedded. 

Imper'fect :   applied  to  a  unisexual  flower. 

Incised' :   sharply  and  irregularly  cut  into.     Fig.  234. 

Inclu'ded :   not  extending  beyond  the  surrounding  envelopes. 

Incomplete' :  wanting  in  one  of  the  floral  envelopes. 

Incum'bent  (L.  incumbens,  leaning  on)  :  said  of  cotyledons  when  reflexed  so 
that  the  back  of  one  lies  against  the  hypocotyl. 

Indefinite :  applied  to  stamens  when  inconstant  in  number,  or  too  numerous 
for  easy  counting.  Said  of  an  inflorescence  whose  main  axis  continues 
to  elongate  as  the  buds  unfold,  as  in  a  raceme ;  applied  to  the  growth  of 
branches  which  continue  to  elongate  throughout  the  growing  season. 

Indehis'cent  (L.  in,  not ;  dehiscens,  gaping)  :  remaining  closed,  or  not  open- 
ing by  valves  or  along  regular  lines. 

Indeterm'inate :  not  absolutely  terminated,  as  when  no  flower  ends  the  axis 
of  an  inflorescence. 

Indig'enous  (L.  indiges,  native)  :  native  to  a  country ;  not  introduced. 

Indu'plicate  (L.  in,  toward ;  duplicare,  to  double)  :  arranged  around  an 
axis  without  overlapping,  with  the  edges  turned  inward.  Fig.  284. 

In'durated  (L.  induratus,  hardened)  :  hardened. 

Indu'sium  (L.  indusium,  an  under  garment)  :  the  covering  over  the  groups 
of  sporangia  or  sori  of  ferns.  Fig.  154. 

Inequilat'eral :  having  right  and  left  sides  of  different  extent. 

Infe'rior:  lower  or  anterior.  Inferior  ovary:  having  the  other  floral  organs 
apparently  growing  from  it,  at  or  near  its  summit.  Fig.  1 23,  C  and  D. 
Inferior  calyx:  growing  below  and  free  from  the  ovary.  Fig.  123,  A. 

Infla'ted:  bladdery. 

Inflores'cence  (L.  inflorescere,  to  begin  to  blossom)  :  the  general  arrange- 
ment of  the  flowers  on  the  flowering  axis. 

In'nate  (L.  innatus,  inborn)  :  said  of  an  anther  when  joined  by  its  base  to 
the  apex  of  a  filament.  Fig.  292. 

Insert'ed :  growing  out  of  or  attached  to. 


412  Introduction  to  Botany. 

In'ternode  (L.  inter,  between ;  nodus,  a  knot)  :  the  portion  of  the  stem  be- 
tween the  nodes  or  places  where  the  leaves  arise. 

Intramar'ginal :  within  and  near  the  margin. 

Intro rse'  (L.  infra,  on  the  inside  ;  versus,  toward)  :  facing  inward  or  toward 
the  axis. 

Invol'ucel  (L.  diminutive  of  involucrum,  a  wrapper)  :  a  secondary  involucre. 

Involu'cral :  pertaining  to  an  involucre. 

Involu'cre  (L.  involucrum,  a  wrapper)  :  an  assemblage  of  bracts  subtending 
a  flower  or  flower  cluster.  Invol'ucrate  :  having  an  involucre. 

In/volute  (L.  involvere,  involutum,  to  wrap  up)  :  rolled  inward.     Fig.   285. 

Irreg'ular:  applied  to  flowers  whose  individual  members  of  a  set  of  organs 
are  unlike  in  form. 

Junc'oid  (L.Juncus,  a  rush  ;  Gr.  eidos,  resemblance)  :  rush-like. 

Keel :  the  two  anterior  or  lower  petals  of  a  papilionaceous  corolla  which  are 
united  in  the  form  of  a  keel  of  a  boat.  Figs.  266  and  267,  k. 

Key  or  key '-fruit:  a  winged  fruit,  such  as  of  the  maple  or  ash;  a  samara. 
Fig.  320. 

Kid'ney-shaped :  crescent-shaped,  with  rounded  ends  ;  reniform.     Fig.  227. 

La'biate  (L.  labium,  lip)  :  having  the  limb  of  calyx  or  corolla  divided  as  in 
Fig.  276.  Belonging  to  the  Labiatse. 

Lac'erate :  irregularly  cleft  or  jagged,  as  if  torn. 

Lacin'iate  (L.  lacinia,  the  flap  of  a  garment)  :  provided  with  a  jagged,  irreg- 
ular fringe. 

Lamel'la  (L.  lamella)  :  a  thin  plate  or  scale. 

Lan'ceolate :  lance-shaped;  narrow  and  tapering  toward  each  end,  as  in 
Fig.  220. 

La'tent  (L.  latens,  hidden)  :  applied  to  buds  which  lie  dormant  for  a  number 
of  years  without  losing  their  power  of  developing  when  conditions  are 
favorable. 

Lat'eral :  borne  on  the  side  of  an  organ. 

La'tex  (L.  latex,  juice)  :  the  milky  secretion  of  such  plants  as  Euphorbia. 

Laticif 'erous  (L.  latex  +  ferre,  to  bear)  :  latex-bearing. 

Lax :  loose  and  slender. 

Leaflet :  one  of  the  separate  divisions  of  a  compound  leaf. 

Leaf -stalk :  the  stem  or  petiole  on  which  the  leaf  is  borne.     Fig.  262,  b. 

Leg'ume  (L.  legumen,  pulse  or  any  leguminous  plant)  :  a  pod  dehiscing  into 
two  valves  and  having  the  seeds  all  attached  on  one  sidfc.  Fig.  313. 

Legu'minous :  pertaining  to  a  legume  or  to  the  order  called  Leguminosae. 


Glossary.  413 

Lentic'ular  (L.  lens,  lentis,  a  lentil  or  its  seed  which  has  a  double  convex 

outline)  :  shaped  like  a  double  convex  lens. 
Lig'ulate :  provided  with  a  ligule. 
Lig'ule  (L.  ligula,  a  little  tongue)  :  a  strap-shaped  body  such  as  the  limb  of 

the  ligulate  corolla  of  the  Composite.     Fig.  268,  q. 
Lilia'ceous:  lily-like;   pertaining  to  the  Liliacese. 
Limb  :  the  border  or  expanded  part  of  a  gamopetalous  corolla;  the  blade  of 

a  leaf  or  petal.     Fig.  272,  y. 

Lin'ear :  long  and  narrow  with  parallel  margins.     Fig.  219. 
Lip :  one  of  the  divisions  of  a  bilabiate  corolla  or  calyx.     Fig.  276. 
Lobe :  any  segment,  but  particularly  a  rounded  segment  of  an  organ. 
Lobed  or  lo'bate  :  divided  into  lobes. 
Loc'ular  (L.  loculus,  a  little  compartment)  :  having  cells. 
Loc'ulicidal  (L.  loculus,  a  cell  or  compartment;   ccedere,  to  cut)  :  dehiscent 

or  breaking  open  through  the  dorsal  suture.     Fig.  322. 
Lo'ment :  a  legume  which  is  contracted  between  the  seeds.     Fig.  314. 
Lu'men  (L.  lumen,  a  light,  an  opening)  :  the  cavity  of  a  cell. 
Lu'nate  (L.  luna,  the  moon)  :  shaped  like  a  half  or  crescent  moon. 
Lu'nulate  :  diminutive  of  lunate. 
Ly'rate  (Gr.  lyra,  a  lute  or  lyre)  :  lyre-shaped;  spatulate  and  lobed,  with  the 

smaller  lobes  toward  the  base. 

Mac'rospore  (Gr.  makros,  long  or  large;  spora,  seed)  :  the  larger  spore  of 
some  Pteridophytes,  which  gives  rise  to  the  female  gametophyte;  the 
embryo  sac  of  Spermatophytes. 

Macrospor'ophyll  (Gr.  makros  +  spora  +  phyllon,  a  leaf)  :  carpel,  carpellary 
leaf. 

Mar'ginal :  along  or  near  the  edge. 

Mar'ginate  :  provided  with  a  border  or  margin  of  distinct  character. 

Membrana'ceous,  or  mem'branous :  thin  and  somewhat  transparent. 

Menis'coid  (Gr.  meniskos,  a  crescent;  tides,  resemblance)  :  concavo-convex, 
like  a  watch  crystal. 

Mer'icarp  (Gr.  meros,  a  part;  karpos,  fruit)  :  one  carpel  of  an  umbelliferous 
fruit. 

-merous :  in  composition  relating  to  a  certain  number  of  parts,  as  2-merous, 
having  two  parts. 

Mes'ophyll  (Gr.  mesos,  in  the  middle;  phyllon,  a  leaf)  :  the  thin-walled  par- 
enchyma cells  which  make  up  the  greater  part  of  the  interior  of  a  leaf. 

Mes'ophyte  (Gr.  mesos  +  phyton,  a  plant):  a  plant  adapted  to  a  habitat 
having  a  moderate  amount  of  humidity  in  atmosphere  and  soil. 

Mesophy t'ic :  -  relating  to  mesophytes. 


414  Introduction  to  Botany. 

Mi'cropyle  (Gr.  mikros,  small;  pyle,  a  gate)  :  the  passage  through  the  coats 
of  an  ovule  through  which  the  pollen  tube  enters;  the  spot  on  or  open- 
ing through  the  coats  of  a  seed  corresponding  to  or  identical  with  the 
opening  of  the  ovule.  P'ig.  88. 

Mi'crospore  (Gr.  mikros,  small;  spora,  seed)  :  the  smaller  spore  of  certain 
Pteridophytes,  which  gives  rise  to  the  male  gametophyte;  the  pollen 
grain  of  Spermatophytes. 

Microspor'ophyll  (Gr.  mikros  -f-  spora  -f  phyllon,  a  leaf):  a  leaf  bearing 
microspores;  a  stamen. 

Mid'rib  :  the  central  or  main  rib  of  a  leaf. 

Monadel'phous :  (Gr.  monos,  one;  adelphos,  brother)  :  applied  to  stamens 
when  united  by  their  filaments  into  a  tube  or  column.  Fig.  290. 

Monil'iform   (L.  monile,  necklace;  forma,  shape)  :  like  a  string  of  beads. 

Monocotyle'don  (Gr.  monos,  one;  kotyledon,  a  hollow) :  a  plant  having  but 
one  cotyledon. 

Monocotyle'donous:  having  but  a  single  cotyledon. 

Monce'cious,  pr.  mo-ne'shus  (Gr.  monos,  one;  oikos,  household)  :  having 
stamens  and  pistils  in  separate  flowers  on  the  same  plant. 

Mucilag'inous :  slimy;  composed  of  mucilage. 

Mu'cro  (L.  mucro,  sword)  :  a  sharp  and  abrupt  tip. 

Mu'cronate :   ending  abruptly  with  a  sharp  point.     Fig.  250. 

Mul'tifid  (L.  mttltus,  many;  findere,  to  split)  :  cleft  into  many  segments. 

Mul'tiple  fruit :  a  fruit  consisting  of  many  ripened  pistils  consolidated  into  a 
mass,  as  in  the  mulberry.  Fig.  327. 

Mu'ricate  (L.  murex,  a  pointed  stone)  :  rough  with  short  hard  points. 

Muric'ulate :  finely  muricate. 

Na'ked :  destitute  of  covering,  as  buds  without  scales. 

Na'piform  (L.  napus,  turnip;  forma,  shape)  :  turnip-shaped.     Fig.  216. 

Na'tant  (L.  natans,  swimming)  :  floating  submerged  in  water. 

Nec'tar  (Gr.  nektar,  the  drink  of  the  gods)  :  a  sweetish  fluid  excreted  from 

some  parts  of  a  flower  for  the  attraction  of  insects. 

Nectariferous  (nectar  +  ~L.ferre,  to  bear  or  produce)  :  nectar-bearing. 
Nec'tary :  any  part  of  a  flower  which  secretes  and  excretes  nectar. 
Nec'tar  recep'tacle  :  a  part  of  a  flower  into  which  the  nectar  is  excreted  and 

conserved,  as  the  spur  of  violets  and  larkspurs. 
Nerva'tion :  the  manner  in  which  the  nerves  are  arranged  in  a  leaf. 
Nerve  :  a  slender  unbranched  vein  or  rib. 
Neu'ter  (L.   neuter,  neither  the  one  nor  the  other)  :  sexless,  as  a  flower 

having  neither  stamens  nor  pistil. 
Neu'tral :  applied  to  flowers  having  neither  stamens  nor  pistil. 


Glossary.  415 

Nod'ding :  hanging  downward. 

Node(L.  nodus,  a  knot) :  that  part  of  a  stem  which  normally  bears  a  leaf  or  leaves. 
Nodose' :  having  many  or  conspicuous  nodes  or  knotty  swellings. 
Nu'cleus  (L.  nucleus,  kernel  or  inner  part)  :  a  well-defined,  and  in  young 
cells,  central  body  of  a  cell,  which  is  thought  to  be  the  bearer  of  the 
inheritable  qualities.     Figs.  12,  45,  and  46. 

Nut:  a  hard,  indehiscent,  usually  I -seeded  fruit,  as  the  walnut  and  acorn. 
"Fig.  334.  Nut'let:  a  small  nut. 

Ob- :  a  Latin  prefix  indicating  inversion. 

Obcla'vate  (L.  ob-,  inverse;  davatus,  club-shaped)  :  club-shaped,  and  at- 
tached at  the  thicker  end. 

Obcompressed' :    compressed  dorsiventrally  instead  of  laterally. 

Obcon'ical  (L.  ob-  -f  conus,  a  cone)  :  conical  and  attached  at  the  narrower  end. 

Obcor'date  (L.  ob-  +  cor,  cordis,  the  heart)  :  heart-shaped  and  attached  at  the 
narrower  end. 

Oblan'ceolate  (L.  ob-  +  lanceola,  a  little  lance)  :  lanceolate  with  the  broadest 
part  toward  the  apex.  Fig.  226. 

Oblique',  pr.  obleek'  or  oblike'  (L.  obliquus,  slanting) :  slanting  or  unequal 
sided. 

Ob 'long :    much  longer  than  broad  and  with  parallel  sides.     Fig.  221. 

Obo'vate  (L.  ob-  +  ovatus,  egg-shaped)  :  egg-shaped  and  attached  at  the 
smaller  end.  Obo'void :  an  obovate  solid. 

Ob'solete  (L.  obsoletus,  worn  out)  :    much  reduced  or  rudimentary. 

Obtuse' :    blunt  or  rounded  at  the  end.     Fig.  249. 

Ochroleu'cous,  pr.  ok-ro-lu'kus  (Gr.  ochra,  yellow  earth;  leukos,  white): 
yellowish  white. 

O'crea  (L.  ocrea,  a  legging)  :  a  tubular  stipule,  or  a  pair  of  stipules  united  in 
the  form  of  a  tube.  Fig.  264,  2. 

O'create  :    provided  with  an  ocrea. 

Odd'ly  pin'nate:  pinnately  compound  and  having  a  terminal  leaflet.  Fig.  255. 

Offic'inal  (L.  officina,  a  workshop)  :    used  in  medicine  or  the  arts. 

Offset  or  off 'shoot :  a  lateral  shoot  which  takes  root  and  starts  a  new  indi- 
vidual. Fig.  211. 

O'ospore  (Gr.  oon,  an  egg ;  spora,  seed)  :   the  fertilized  egg  cell. 

Opaque':    dull;   not  transparent. 

Oper'culum  (L.  operculum,  cover,  lid)  :  the  upper  half  of  a  capsule  which 
dehisces  transversely.  Figs.  150  and  325. 

Op'posite  :    said  of  leaves  when  two  stand  on  opposite  sides  at  a  node. 

Orbic'ular  (L.  orbicularis,  circular)  :  flat  with  circular  contour.  Figs.  225 
and  246.  . 


41 6  Introduction  to   Botany. 

Orthot'ropOUS  (Gr.  orthos,  upright;  trope,  a  turning)  :  applied  to  an  erect 
ovule  or  seed  having  the  micropyle  at  the  apex.  Fig.  298. 

O'val  (L.  ovum,  an  egg)  :    broadly  elliptic. 

O'vary :    that  part  of  the  pistil  which  contains  the  ovules.     Fig.  87. 

O'vate :  having  the  outline  of  a  hen's  egg,  with  broader  end  down.     Fig.  223. 

O'void :    a  solid  with  an  oval  outline. 

O'vule :  the  body  which,  after  the  fertilization  of  the  egg,  becomes  the  seed. 
Fig.  87.  Ovulif  'erous  (ovule  +  L.  ferre,  to  bear)  :  bearing  ovules. 

Pal'ate  (L.  palatum,  the  palate)  :  in  a  bilabiate  corolla  a  projection  from  the 
lower  lip  closing  the  throat.  Fig.  275. 

Pale  (L.  palea,  chaff )  :  chaffy  scales  on  the  receptacle  of  some  Compositse. 
The  inner  bract  of  a  spikelet  in  the  inflorescence  of  grasses  (in  this  sense 
most  commonly  called  palet). 

Palea'ceous:    chaffy. 

Pal'et :    the  inner  bract  in  the  spikelet  of  grasses. 

Palisade'  cells  (L.  palus,  a  stake)  :  in  leaves  or  stems  elongated  chlorophyll- 
bearing  cells  with  long  axis  perpendicular  to  the  surface.  Fig.  36. 

Pal 'mate  (L.  palma,  the  hand)  :  lobed  or  divided,  with  the  sinuses  directed 
toward  the  petiole.  Figs.  237-239. 

Pal'mately :    in  a  palmate  manner. 

Pan'icle  (L.  panicula,  a  tuft)  :    a  compound  raceme  or  corymb. 

Pan'icled  or  panic'ulate :  borne  in  a  panicle. 

Papiliona'ceous  (L.  papilio,  butterfly)  :  having  a  winged  corolla  somewhat 
resembling  a  butterfly,  as  found  in  the  pea  and  locust.  Figs.  266  and  267. 

Papil'la,  pi.  papillae  (L.  papilla,  a  nipple)  :    a  minute  rounded  projection. 

Pap'illose :    covered  with  or  resembling  papillae. 

Pap'pus  (L. pappus,  an  old  man;  or  a  woolly,  hairy  seed  of  certain  plants)  : 
thistledown;  the  hairy  calyx-limb  of  certain  Compositse.  Figs.  316-318. 

Par'asite  (Gt.para,  beside;  sitein,  to  feed)  :  an  organism  subsisting  on  an- 
other called  the  host. 

Parasit'ic :    living  as  a  parasite  on  another  organism. 

Paren'chyma  (Gr.  para,  beside;  en,  in;  chein,  to  pour):  applied  to  cells 
which  are  more  or  less  isodiametric. 

Pari'etal  (L.  paries,  a  wall  or  partition  wall)  :  applied  to  ovules  attached  to 
the  wall  of  the  ovary  instead  of  to  the  axis.  Figs.  303  and  304. 

Part'ed :    cleft  nearly  to  the  base  or  midrib.     Fig.  235. 

Par'tial :    sometimes  used  in  the  sense  of  secondary. 

Pathogen'ic  (Gr.  pathos,  disease;  genos,  descent)  :    producing  disease. 

Pec'tinate  (L.  pecten,  a  comb)  :  having  narrow  close  divisions  like  the  teeth 
of  a  comb. 


Glossary.  417 

Ped'ate  (L.  pes,  pedis,  a  foot)  :  palmately  parted  or  divided,  with  the  lateral 
segments  again  cleft. 

Ped'icel  (L.  pedictihis,  a  little  foot)  :    the  stalk  of  a  single  flower  of  a  cluster. 

Ped'icellate  :    having  a  pedicel. 

Pedun'cle :  the  stalk  of  a  solitary  flower,  or  the  primary  flower  stalk  of  a 
cluster.  Pedun/culate :  borne  on  a  peduncle. 

Pellu'cid  (L.  per,  through;  lucidus,  clear,  luminous)  :  transparent  or  nearly  so. 

Pel'tate  (L.  pelta,  a  shield)  :  shield-shaped,  and  attached  at  its  lower  surface 
instead  of  by  its  margin.  Fig.  246. 

Pen'dulous :  applied  to  an  ovule  which  hangs  downward  from  the  side  of  the 
ovary. 

Pe'po  (Gr.  pepon,  a  kind  of  gourd  or  melon)  :  a  kind  of  berry  with  a  firm, 
hard  rind,  such  as  the  pumpkin  or  gourd.  Fig.  338. 

Peren'nial  (L.  perennis,  that  lasts  the  whole  year  through;  from  per, 
through;  annus,  the  year)  :  lasting  from  year  to  year. 

Per'fect :    applied  to  flowers  having  both  pistil  and  stamens. 

Perfo'liate  (L.  per,  through  ;  folium,  a  leaf)  :  said  of  a  leaf  having  the  stem 
apparently  passing  through  it.  Fig.  244. 

Per'ianth  (Gr.  peri,  about ;  anthos,  a  flower)  :  calyx  or  corolla,  or  both  col- 
lectively when  present. 

Per'icarp  (Gt.peri,  about;   karpos,  fruit)  :   the  matured  ovary  or  its  wall. 

Perigyn'ium  (Gr.  peri  +  gyne,  woman)  :  the  inflated  sac  inclosing  the  ovary 
in  Carex. 

Perig'ynous :  borne  above  the  base  of  the  ovary  but  not  at  its  summit.  Fig. 
123,  B. 

Persis'tent :  continuing  long,  as  sepals  on  the  maturing  fruit  or  leaves  re- 
maining on  their  branches  through  the  winter. 

Per'sonate  (L.  personatus,  masked) :  applied  to  a  bilabiate  corolla  having  the 
throat  closed  by  a  prominent  projection  or  palate.  Fig.  275. 

Pet'al  (Gr.  petalon,  a  leaf)  :    one  of  the  parts  of  the  corolla.     Fig.  87. 

Pet'aline,  pr.  pet'al-in :    pertaining  to  or  resembling  a  petal. 

Pet'aloid :    colored  and  resembling  a  petal. 

Pet'iolate  (L.  petiolus,  a  little  foot  or  leg)  :  having  a  petiole. 

Pet'iole  :  the  footstalk  of  a  leaf.     Fig.  262,  b. 

Phsenog'amous  (Gr.  phainein,  to  show;  gamos,  marriage)  :  having  flowers  in 
the  ordinary  sense  of  the  word,  and  producing  seeds. 

Phan'erogam  or  phaneroga'mia  (Gr.  phaneros,  evident;  gamos  marriage)  : 
a  plant  or  class  of  plants  having  flowers  in  the  ordinary  sense,  and  pro- 
ducing seeds. 

Photosyn'thesis  (Gr. phos,  photos,  light ;  synthesis,  a  putting  together):  the 
formation  of  starch  and  sugars  from  carbon  dioxide  and  water  by  means 


41 8  Introduction  to  Botany. 

of  the  chloroplasts,  which  derive  their  energy  for  the  work  from  the  light 

absorbed  by  the  chlorophyll. 
Phyllo'dium  (Gr.  phyllon,  leaf;    eidos,  form)  :    a  petiole  expanded  into  the 

form  of  a  leaf  blade.     Fig.  261. 
Phyl'lotaxy  (Gr.  phyllon,  leaf;  taxis,  arrangement)  :  the  angular  distribution 

of  leaves  on  the  stem. 
Phy'tomer  (Gr.  pkyton,  plant;   meros,  part)  :    a  node  with  its  leaf  or  leaves, 

and  the  internode  subtending  it. 
Pi'lose  (L.  pilus,  a  hair)  :  beset  with  soft  hairs. 
Pin'na  (L.  pinna,  a  feather)  :   one  of  the  primary  divisions  of  a  pinnate,  or 

pinnately  compound,  leaf. 
Pin'nate :   compound,  with  the  leaflets  arranged  on  each  side  of  a  common 

petiole.     Figs.  255  and  256.     Oddly  pinnate :  with  a  single  terminal  leaf- 
let.    Fig.  255.     Abruptly  pinnate :  all  of  the  leaflets  in  pairs,  and  no  ter- 
minal leaflet  present.     Fig.  256. 
Pinnat'ifid  (L.  pinna  +  finder e,  fidi,  to  cut)  :   divided  in  a  pinnate  manner, 

but  not  as  far  as  the  midrib.     Fig.  235. 
Pin'nule  :  a  secondary  pinna. 

Pis'til    (L.  pistillum,  a  pestle)  :    the   female  spore-bearing  leaf,  or  leaves 
,    united,  of  Spermatophytes,  consisting  of  ovary,  stigma,  and  commonly 
X  style.     Fig.  87. 
Pis'tillate :  having  pistils,  and,  as  the  term  is  commonly  employed,  destitute 

of  stamens. 

Pitted  :  having  small  depressions  over  the  surface. 
Placen'ta  (L.  placenta,  a  flat  cake)  :    that  part  of  the  interior  of  the  ovary 

which  bears  the  ovules.     Figs.  302-305. 
Plasm  or  plasma  (Gr. plasma,  anything  formed  or  molded)  :  protoplasm;  the 

living  part  of  the  plant  or  animal  body. 
Plasma  membrane :  the  limiting  protoplasmic  membrane  at  the  exterior  of 

plant  cells  which  are  destitute  of  cell  walls,  or  the  membrane  which  lies 

in  immediate  contact  with  the  wall  when  the  latter  is  present.     Fig.  12. 
Plasmo'dium :  a  multinucleated  mass  of  protoplasm  destitute  of  cell  walls,  and 

capable  of  amoeboid  movement.     Fig.  132. 
Plas'tM  (Gr.  plastis,  plastidos,  a  creator)  :  a  differentiated  portion  of  the  cell 

protoplasm  having  definite  work  to  do,  such  as  the  manufacture  of  starch, 

chlorophyll,  and  other  pigments. 

Pli'cate  (L.  plicare,  to  fold  or  plait)  :  folded  like  a  fan. 
Plu'mose  (L.  pluma,  a  feather)  :  having  hairs  on  each  side  like  the  plume  of 

a  feather. 

Plu'mule  (L.  plumula,  a  little  feather)  :  the  first  bud  of  the  embryo. 
Pod :  a  dry  and  dehiscent  fruit,  such  as  a  legume  or  silique.     Figs.  309  and  313. 


Glossary.  419 

Pol'len  (L.  pollen,  fine  flower)  :  the  microspores  of  Spermatophytes  which  are 

borne  within  the  anthers,  and  give  rise  to  the  sperms  or  fertilizing  cells. 
Pol'len  cells  or  sacs :  the  cavities  of  the  anther  which  contain  the  pollen. 
Pol'len  grain:  a  single  microspore  of  Spermatophytes. 
Pol'len  tube :  the  tubular  outgrowth  from  the  pollen  grain,  which  penetrates 

the  pistil  and  conducts  the  sperm  into  the  ovule.     Fig.  88. 
Pollinate  :  to  apply  pollen  to  the  surface  of  the  stigma. 
Pollinif  erous  (L.  pollen  +  ferre,  to  bear)  :  pollen-bearing. 
Pollin'ium :    a  coherent  mass  of  pollen,  as  in  the  milkweed  and  orchids. 

Fig.  113. 
Polyadel'phic  (Gr.  polys,  many;   adelphos,  a  brother)  :    having  the  stamens 

united  into  several  bundles  or  brotherhoods. 

Polypet'alous  (Gr.  polys,  many;  /*?/a/0«,aleaf)  :  having  several  separate  petals. 
Poma'ceous  (L.  pomum,  a  fruit  of  any  kind)  :  like  an  apple  or  pear;  produc- 
ing pomes. 

Pome  :  a  fruit  of  the  apple,  pear,  and  quince  type.     Fig.  333. 
Pore :  any  small  aperture,  as  in  some  anthers  for  the  discharge  of  pollen. 
Por'ous  or  porose' :  pierced  with  small  openings  or  pores. 
Poste'rior:  next  to  or  toward  the  main  axis;   superior. 
Pos'ticous  (L.  posticus,  posterior)  :  situated  on  the  outer  side  of  a  filament,  as 

an  extrorse  anther. 

Praemorse'  (L.  prcz,  before;   mordere,  to  bite)  :  appearing  as  if  bitten  off. 
Prick'le  :  outgrowths  of  the  epidermis  or  of  the  bark,  with  sharp  point. 
Prismat'ic  (L.  prisma,  a  prism)  :   having  the  form  of  a  prism;   angular  with 

flat  sides. 

Procum'bent  (L.  pro,  forward;   cumbens,  lying  down)  :  lying  on  the  ground. 
Proliferous  (L.  proles,  offspring;  ferre,  to  bear)  :  producing  offshoots. 
Pros'trate :  lying  flat  upon  the  ground. 
Proteran'drous  or  protan'drous  (Gr.  proteros,  first;  aner,  andros,  a  man): 

having  the  anthers  mature  before  the  stigmas  of  the  same  flower  are 

ready  to  receive  the  pollen. 
Proteran'dry  or  protan'dry:  the  condition  of  having  the  anthers  mature 

before  the  stigmas. 
Proterog'ynous  or  protog'ynous  (Gr.  proteros,  first;  gyne,  a  woman)  :  having 

the  stigmas  ready  to  receive  the  pollen  before  the  anthers  of  the  same 

flower  are  mature. 
Proterog'yny  or  protog'yny:   the  condition  of  having  the  stigmas  mature 

before  the  anthers. 
Prothal'lus   or  Prothallium   (Gr.  pro,  before;    thallos,  a  young  shoot   or 

sprout)  :   the  gametophyte  of  ferns  and  other   Pteridophytes,  resulting 

from  the  germination  of  an  asexual  spore.     Fig.  155. 


4-2O  Introduction  to  Botany. 

Prox'imal  (L.  proxitnus,  nearest,  next)  :  the  part  nearest  the  axis. 
Pter'idophyte  (Gr.  pteris,  pteridos,  a  kind  of  fern,  from  pteron,  a  feather; 

phyton,  a  plant) :  ferns  and  their  allies. 

Puber'ulent  (L.puber,  of  ripe  age,  pubescent)  :  minutely  hairy. 
Pubes'cence  :  a  covering  of  short  soft  hairs. 
Pubes'cent  (L.  pubescens,  reaching  maturity,  growing  hairy)  :    covered  with 

soft  or  downy  hairs. 

Pul'vinate  (L.  pulvinus,  a  cushion)  :  having  the  form  of  a  cushion  or  pad. 
Pul'vinus :    the  motor  organ  at  the  base  of  some  leaves  and  leaflets,  as  in 

scarlet  runner.     Figs.  59  and  60. 
Punc'tate  (L.  punctum,  a   point)  :    marked  with    depressions,    translucent 

glands,  or  colored  spots. 
Punctic'ulate :  minutely  punctate. 

Pun'gent  (L.  pungens,  piercing)  :  ending  in  a  sharp  and  rigid  point. 
Pus'tular  (L.  pustula,  a  pimple)  :  having  blister-like  elevations. 
Pus'tulate  :  as  though  blistered. 
Puta'men,  pr.  pew-ta'men  (L.  putamen,  shells  or  peels)  :  the  shell  of  a  nut; 

the  stone  of  a  stone  fruit. 
Pyram'idal :  shaped  like  a  pyramid. 

Race  :  a  variety  of  such  fixity  as  to  be  reproduced  by  seeds. 

Raceme'  (L.  racemus,*  bunch  of  grapes)  :  a  simple  inflorescence,  elongating 

at  the  apex,  with  pedicels  of  the  individual  flowers  of  about  equal  length. 

Fig.  82,  r.     Rac'emose :  borne  in  racemes ;   raceme-like. 
Ra'chis  or  rhachis  (Gr.  rhachis,  a  backbone)  :  the  axis  of  an  inflorescence, 

compound  leaf,  or  frond. 
Ra'diate  (L.  radius,  spoke  of  a  wheel)  :   divergent  from  a  common  center ; 

bearing  ray  flowers. 
Rad'ical  (L.  radix,  a  root)  :  belonging  to  or  proceeding  from  the  root,  or 

from  the  base  of  the  stem  close  to  the  ground. 
Rad'icle :    the    name    sometimes   given   to    the   whole   of  the    hypocotyl, 

but  more   properly  restricted  to   the   embryo  root   at   the  tip  of  the 

hypocotyl. 

Radic'ulose :  bearing  rootlets. 
Ra'dix :  the  root  developed  from  the  radicle. 

Ra'phe    or   rha'phe,  pr.  ra'phy  (Gr.  rhaphe,  a  suture  or  seam)  :    the  con- 
tinuation of  the  seed  stalk   along  the   side   of  an  anatropous  ovule. 

Fig.  300. 

Ray :  the  marginal  portion  of  a  composite  flower  ;   a  branch  of  an  umbel. 
Ray  flower  or  flor'et :  an  outer  flower  of  the  head  of  the  Compositae,  whether 

tubular  or  ligulate.     Fig.  268. 


Glossary.  421 

Recep'tacle  (L.  receptaculum,  a  reservoir)  :  the  axis  of  a  flower,  from  which 

spring  sepals,  petals,  stamens,  and  pistils  ;   or  the  axis  which  bears  the 

separate  flowers  of  a  head.     Fig.  87,  a,  and  Fig.  82,  /  and  u. 
Recurved' :  curved  backward  or  downward. 
Redu'plicate  (L.  reduplicatus,  doubled)  :  doubled  back ;   applied  to  leaves 

in  the  bud  with  edges  valvate  and  turned  outward. 
Reflexed' :  abruptly  bent  downward. 
Reg'ular  (L.  regularis,  according  to  rule)  :  applied  to  flowers  having  all  the 

parts  of  a  whorl  uniform  in  shape,  as  when  the  petals  are  all  alike,  etc. 
Ren'iform  (L.  rents,   the   kidneys ;  forma,  shape)  :    kidney-shaped.     Fig. 

227. 

Repand'  (L.  repandus,  bent  backward  or  turned  up) ;   applied  to  leaves  hav- 
ing slightly  undulating  margins.     Fig.  232. 

Re'pent  (L.  repens,  creeping)  :  prostrate  and  rooting.     Fig.  211. 
Resinif  'erous  (L.  resina,  rosin  ;  ferre,  to  bear)  :  resin-bearing. 
Retro rse'  (L.  retro,  back  ;   versus,  toward)  :  bent  downward  or  backward. 
Retuse'  (L.  retusus,  blunted)  :  having  the  apex  rounded  and  slightly  indented. 

Figs.  221  and  253. 
Rev'olute  (L.  revolvere,  revolutum,  to  roll  back  or  unwind)  :  rolled  backward 

or  downward. 
Rha'chis :  see  Rachis. 
Rha'phe :  see  Raphe. 
Rhi'zoid  (Gr.  rhiza,  a  root ;  eidos,  form)  :  a  hair  serving  as  a  root  in  mosses 

and  Hepaticae. 
Rhizome'  (Gr.  rhizoma,  a  mass  of  roots,  a  stem  or  race)  :  a  prostrate  under* 

ground  stem,  rooting  at  the  nodes,  and  erect  and  leaf-  or  stem-bearing  at 

the  apex;   or  short  and  variously  thickened,  quite  variable  in  appearance. 

Figs.  205-210. 
Rhom'bic  or  rhomboid 'al  (Gr.  rhombos,  a  spinning  top)  :  shaped  like  a  rhomb, 

—  namely,  a  quadrilateral  figure  with  parallel  and  equal  sides  which  may 

be  either  oblique  or  perpendicular  to  each  other. 
Rib  :  a  prominent  vein.     Ribbed :  having  prominent  parallel  veins. 
Rin'gent   (L.  ringens,  gaping) :   wide  open,  as  the  mouth  of  a  bilabiate 

corolla. 

Root 'stock :  see  Rhizome. 

Ros'trate  (L.  rostrum,  a  beak)  :  provided  with  a  point  or  beak. 
Ro'tate  (L.  rota,  a  wheel)  :  wheel-shaped  ;  flat  and  circular.     Fig.  274. 
Rotund' :  rounded  in  outline. 

Ru'fous  (L.  rufus,  red  or  reddish)  :  reddish,  yellowish  red,  or  tawny. 
Rugose'  (L.  ruga,  a  wrinkle)  :  wrinkled ;  having  the  veinlets  sunken  and  the 

spaces  between  elevated,  as  in  the  leaves  of  sage. 


422  Introduction  to  Botany. 

Run'cinate  (L.  runcina,  a  large  saw)  :  deeply  incised,  with  the  lobes  point- 
ing toward  the  base  of  the  petiole,  as  in  the  dandelion  leaf.     Fig.  32. 
Run'ner  :  a  prostrate  lateral  offshoot  rooting  at  the  nodes.     Fig.  211. 

Sac'cate  (L.  saccus,  a  bag)  :  bag-shaped. 

Sag'ittate  (L.  sagitta,  an  arrow)  :  arrow-shaped ;  having  two  acute  lobes  at 
the  base  like  the  barbs  of  an  arrow.  Fig.  243. 

Sal'ver-form  or  sal'ver-shaped :  tubular,  with  a  spreading  border.    Fig.  273. 

Sama'ra  (L.  samara  or  samera,  the  fruit  of  the  elm)  :  an  indehiscent  winged 
'  fruit  like  that  of  the  maple  and  elm.  Figs.  319  and  320. 

Sapona'ceous  (L.  sapo,  soap)  :  soapy  or  slippery  to  the  touch. 

Sap-wood :  the  new  wood  of  exogenous  woody  plants,  of  lighter  color  and 
of  less  specific  gravity  than  the  older  heart-wood. 

Sca'brous  (L.  sealer,  rough)  :  rough  to  the  touch. 

Scan/dent  (L.  scandens,  climbing)  :  climbing  in  any  manner. 

Scape  (L.  scapus,  a  shaft  or  stem) :  a  leafless  floral  axis  or  peduncle  rising 
from  the  ground. 

Sca'pose  :  bearing  or  resembling  a  scape. 

Sca'riose  or  sca'rious  (L.  scariosus)  :  dry  and  membranous. 

Scor'pioid  (Gr.  skorpios,  a  scorpion  ;  eidos,  resemblance)  :  having  the  axis  of 
the  inflorescence  coiled  to  one  side. 

Scor'pioid-cyme :  a  cyme  whose  lateral  branches  occur  alternately  on  oppo- 
site sides. 

Scurf :  bran-like  scales  over  the  epidermis. 

Seed :  the  ripened  ovule  and  its  integuments. 

Seg'ment :  one  of  the  parts  of  a  cleft  or  divided  member  ;  one  of  the  simi- 
lar parts  of  a  series. 

Sep'al  or  se'pal  (L.  separ,  separate)  :  one  of  the  divisions  of  the  calyx. 

Sep'ticidal  (L.  septum  -f  ccedere,  to  cut)  :  a  method  of  dehiscence  in  which 
the  pod  is  divided  through  the  middle  of  the  partitions.  Fig.  321. 

Septif'ragal  (L.  septum ;  frangere,  fractum,  to  break):  a  mode  of  dehis- 
cence in  which  the  valves  break  away  from  the  partition  walls.  Figs. 
323  and  324. 

Sep'tum,  pi.  septa  (L.  septum,  a  wall  or  fence)  :  the  division  wall  of  an  ovary. 

Ser'rate  (L.  serra,  a  saw)  :  having  forward-pointing  marginal  teeth.    Fig.  229. 

Ser'rulate :  finely  serrate. 

Ses'sile  (L.  sessilis,  sitting)  :  not  provided  with  a  stalk. 

Seta'ceous  (L.  seta,  a  bristle)  :  bristle-like. 

Se'tiform:  having  the  form  of  a  bristle. 

Setose' :  beset  with  bristles  or  bristly  hairs. 

Se'tulose  :  resembling  or  beset  with  fine  bristles. 


Glossary.  423 

Sex :  pertaining  to  a  differentiation  into  male  and  female. 
Sex'ual-genera'tion :  the  stage  or  generation  in  the  life  cycle  which  bears 

the  eggs  and  sperms,  as  the  prothallus  of  ferns.     Figs.  157,  158,  and  159. 
Sheath :  a  tubular  covering,  such  as  the  lower  part  of  the  leaves  of  grasses. 
Sheathing :  inclosing  after  the  manner  of  a  sheath. 
Shoot :  the  ascending  axis  or  branch  therefrom  with  its  leaves. 
Shrub  :  a  woody  plant  smaller  than  a  tree.     Shrubby :  resembling  a  shrub. 
Sil'icle  (L.  silicula,  a  little  husk  or  pod)  :  a  short  pod  scarcely  longer  than 

broad.     Fig.  310. 
Silique',  pr.  si-leek'  (L.  siliqua,  a  husk  or  pod)  :    an  elongated  pod  divided 

by  a  partition  and  opening  by  two  sutures,  as  in  the  Cruciferse.    Fig.  309. 
Silky :   beset  with  a  soft  and  straight  pubescence. 
Simple:    undivided;    applied  to   pistils   and   fruits   consisting  of  a  single 

carpel. 
Sin'uate  or  sin'uous  (L.  sinuosus,  full  of  windings  or  curves)  :   having  a 

strongly  wavy  margin.     P'ig.  232. 

Si'nus  (L.  sinus,  a  curve,  hollow,  or  fold)  :    the  recess  between  two  lobes. 
So'rus,  pi.  sori  (Gr,  soros,  a  heap)  :    a  fruit  dot,  or  cluster  of  sporangia  in 

ferns. 

Spadi'ceous  (Gr.  spadix,  a  palm  branch)  :    resembling  or  bearing  a  spadix. 
Spa'dix :    a  spike  with  a  fleshy  axis,  as  in  calla  lily  and  Jack-in-the-pulpit. 

Fig.  346. 

Spathe,  pr.  spath  (Gr.  spathe,  a  spatula)  :    a  large  bract  or  pair  of  bracts  in- 
closing a  flower  or  inflorescence.    Fig.  346. 
Spat'ulate  (L.  spatula,  a  broad  piece,  or  a  palm  branch)  :  narrowing  toward 

the  base  from  a  rounded  summit.     Fig.  228. 
Sperm  (Gr.  sperma,  a  seed)  :    the  male  reproductive  cell. 
Sperm'atophyte  (Gr.  sperma,  spermatos,  a  seed;  phyton,  a  plant)  :   a  plant 

bearing  true  seeds  with  differentiated  embryos. 

Spi'cate  (L.  spica,  an  ear  of  grain,  as  of  corn  or  wheat)  :   borne  in  or  re- 
sembling a  spike. 
Spike :    an  inflorescence  having  the  flowers  nearly  or  quite  sessile  upon  an 

elongated  axis.     Fig.  82,  s.     Spike 'let :  a  small  or  secondary  spike. 
Spin'dle-shaped :   see  Fusiform. 

Spine  (L.  spina,  a  thorn) :    a  sharp  woody  outgrowth  from  a  stem. 
Spi'nose  or  spi'nous  :   beset  with  spines. 
Spi'nulose  :    beset  with  small  spines. 
Sporan'gium  (Gr.  spora,  a  seed;   aggeion,  a  vessel)  :    a  sac  containing  spores. 

Fig.  154. 
Spore :    a  reproductive  cell  of  Cryptogams  capable  of  growing  into  a  mature 

plant. 


424  Introduction  to   Botany. 

Spur :  a  hollow  extension  of  some  part  of  a  flower,  usually  for  the  purpose  of 
conserving  the  nectar. 

Squa'ma  (L.  squama,  a  scale)  :    a  scale  of  any  kind. 

Squa'mula :   a  reduced  scale. 

Squar'rose,  pr.  skwor'ros  or  skwor-ros'  (L.  squarrosus,  rough,  scurfy)  :  hav- 
ing spreading  and  projecting  processes. 

Squar'rulose :    diminutively  squarrose. 

Sta'men  (Gr.  stemon,  a  thread)  :  the  male  spore-bearing  leaf  of  Spermato- 
phytes,  consisting  of  anther  and  filament.  Figs.  87  and  288-297. 

Stam'inal :    relating  to  or  consisting  of  stamens. 

Stam'inate;    usually  applied  to  flowers  having  stamens  hut  no  pistils. 

Stamino'dium  (stamen  +  Gr.  eidos,  resemblance)  :  a  sterile  or  abortive  stamen 
or  its  homologue,  in  which  the  anther  is  wanting  or  undeveloped.  Fig.  277. 

Stand'ard :    the  upper  dilated  petal  of  a  papilionaceous  flower.     Fig.  266,  s. 

Stel'late  (L.  stella,  a  star)  :    star-shaped. 

Ster'ile  (L.  sterilis,  barren,  unfruitful)  :  applied  to  a  flower  without  a  pistil, 
or  to  a  stamen  wanting  an  anther. 

Stig'ma  (Gr.  stigma,  a  point)  :  that  part  of  the  pistil  which  is  adapted  to 
receive  and  hold  the  pollen  and  permit  the  penetration  of  the  pollen 
tube.  Fig.  87,  h.  Stigmat'ic:  pertaining  to  a  stigma. 

Stipe  (L.  stipes,  stalk  or  trunk)  :  the  leafstalk  of  a  fern;  the  stalk  at  the  base 
of  some  pistils,  lifting  them  above  the  insertion  of  the  other  floral  organs; 
the  stem  which  bears  the  cap  or  pileus  of  toadstools  and  their  kind. 

Stip'itate :    having  a  stipe. 

Stip'ular  (L.  stipula,  stem  or  stubble)  :    pertaining  to  a  stipule. 

Stip'ulate :    having  stipules. 

Stip'ule  (L.  stipula,  stem  or  stubble)  :  one  of  two  similar  appendages  fre- 
quently occurring  on  either  side  of  the  insertion  of  a  leaf  on  the  stem. 
Fig.  262,  c, 

Sto'lon  (L.  stolo,  a  sucker  or  shoot  springing  from  the  base  of  a  plant)  :  any 
basal  shoot  which  is  disposed  to  lie  prostrate  or  bend  downward  and 
strike  root.  Fig.  211. 

Stolonif'erous  (L.  stolo  -\-ferre,  to  bear)  :   producing  stolons. 

Stoma,  pi.  sto'mata  (Gr.  stoma,  a  mouth)  :  an  orifice  in  the  epidermis  of 
leaves  and  some  other  plant  members,  bounded  by  two  guard  cells,  which 
usually  have  the  power  to  draw  apart  or  close  together  as  the  interchange 
of  gases  or  the  reduction  of  transpiration  through  the  orifice  may  be  de- 
manded. Figs.  35  and  40. 

Stone-fruit :  a  fruit  with  a  central  stone,  as  in  the  peach  and  plum.    Fig.  332. 

Striate  (L.  stria,  a  furrow)  :  marked  with  fine  longitudinal  grooves  and 
ridges. 


Glossary.  425 


Strict  (L.  strictus,  close,  straight)  :    straight  and  upright. 

Stri'gose   (L.   strigosus,  thin   and   meager) :    beset   with  .  appressed,   sharp, 

straight,  and  stiff  hairs  or  bristles. 
Strob'ile,  pr.  strob'il  or  stro'bile   (Gr.  strobiles,  a  cone)  :    an  inflorescence 

with  imbricated  scales,  as  in  the  hop  and  the  pine  cone.     Fig.  93. 
Style  (Gr.  stylos,  a  pillar)  :    the  elongation  from  the  top  of  the  ovary,  usually 

present,  which  bears  the  stigmas.     Fig.  87. 
Stylopo'dium  (Gr.  stylos,  a  pillar;  podion,  diminutive  of  pous,  podos,  foot)  : 

a  disk-like  expansion  at  the  base  of  a  style,  as  in  the  Umbelliferse. 
Sub-,  a  Latin  prefix  in  compound  botanical  terms,  usually  signifying  somewhat 

or  slightly. 

Su'bulate  (L.  subula,  an  awl)  :    awl-shaped. 
Suc'culent  (L.  suculentus,  full  of  juice  or  sap)  :  juicy  or  sappy. 
Suffrutes'cent  (L.  sub,  somewhat;  frutex,  a  shrub)  :   slightly  woody  at  the 

base. 
Suffru'ticose  (L.  sub,  somewhat  or  under;  fruticosus,  shrubby)  :   woody  near 

the  base,  and  producing  annual  herbaceous  shoots. 
Sul'cate  (L.  sulcatus,  furrowed)  :    grooved  or  furrowed. 
Sulfu'reous  or  sulphu'reous :   pale  yellow. 
Supe'rior :    applied  to  the  ovary  when  the  other  floral  organs  are  borne  on 

the  receptacle  beneath  it;   applied  to  the  other  floral  organs  when  they 

are  borne  on  an  elongation  of  the  receptacle  or  so-called  calyx  tube, 

above  the  ovary,  or  are  apparently  adherent  to  the  ovary.     Fig.  123. 
Suspend'ed :  applied  to  an  ovule  which  hangs  from  the  top  of  the  cell  of  the 

ovary.     Fig.  306. 
Su'ture  (L.  sutura,  a  seam)  :    an  apparent  juncture  or  seam  of  union;  a  line 

of  dehiscence. 
Syco'nium  (Gr.  sykon,  a  fig)  :  a  fruit  consisting  of  a  fleshy  hollow  receptacle 

lined  with  numerous  flowers,  as  in  the  fig.     Fig.  339. 
Symmetrical :    having  the  same  number  of  parts  in  the  successive  circles 

of  sfloral  organs. 
Syngene'sious  (Gr.  syn,  with,  together;  genesis,  generation  or  birth)  :    said 

of  stamens  which  are  united  by  their  anthers.     Fig.  288. 

Tailed  :  having  a  slender  terminal  prolongation. 

Tap-root :  a  primary  descending  root  forming  a  direct  continuation  of  the 

radicle.     Fig.  215. 

Terete'  (L.  teres,  rounded)  :  having  a  circular  transverse  section;  cylindrical. 
Ter'mlnal :  pertaining  to  the  apex,  as  a  bud  at  the  end  of  a  shoot. 
Ter'nary  (L.  ternarius,  consisting  of  threes)  :  occurring  in  threes. 
Ter'nate  (L.  terni,  by  threes)  :  in  threes. 


426  Introduction  to  Botany. 

Ter'nate-pin'nate  :  applied  to  compound  leaves  when  the  secondary  petioles 

occur  in  threes  at  the  summit  of  the  primary  petiole. 
Tes'ta  (L.  testa,  a  brick  or  tile)  :  the  usually  hard  and  brittle  outer  coat  of  a 

seed. 

Testa'ceous :  brick-red. 
Tetradyn'amous  (Gr.  tetra,  four;  dynamis,  power)  :  having  four  long  and 

two  shorter  stamens,  as  in  the  Cruciferae. 
Tetrag'onal  (Gr.  tetra  -f  gonia,  an  angle)  :  four-angled. 
Thal'loid :  resembling  or  consisting  of  a  thallus. 
Thal'lophyte  (Gr.  thallos,  a  sprout;  phyton,  a  plant)  :  a  plant  having  no 

clear  differentiation  into  stem  and  leaf. 

Thal'lus,  pi.  thalli :  a  vegetative  body  having  no  distinction  into  stem  and  leaf. 
Throat :  the  opening  into  the  tube  of  a  gamopetalous  corolla. 
Thyrse,  pr.  thers  (Gr.  thyrsos,  the  staff  of  Bacchus  twined  round  with  ivy  and 

vine  shoots)  :  a  dense  panicle  like  that  of  the  lilac  or  grape. 
Thyr'soid  (thyrse  +  Gr.  eidos,  resemblance)  :  resembling  a  thyrse. 
Thyr'sus :  same  as  thyrse. 
To'mentose  (L.  Momentum,  a  stuffing  for  cushions  of  wool,  hair,  or  feathers) : 

covered  with  dense  and  matted  woolly  hairs. 

Torose'  (L.  torosus,  fleshy)  :  cylindrical  with  alternate  swellings  and  con- 
tractions.    Tor'ulose :  diminutive  of  torose. 

Tor'us  (L.  torus,  a  bed)  :  the  receptacle  of  a  flower.     Fig.  87,  a. 
Tri  (Gr.  or  L.  prefix  tri,  three)  :  in  compound  words,  three  or  thrice. 
Trian'drous  (tri  +  Gr.  aner,  "andros,  man)  :  having  three  stamens. 
Trich'ome  (Gr.  trichoma,  a  growth  of  hair)  :  any  hair-,  scale-,  or  bristle-like 

outgrowth  from  the  epidermis. 

Tri'fid  (L.  tri,  three -,  finder  e,  fidi,  to  split)  :  three  cleft. 
Trifol'iate  (L.  tri,  three;  folium,  a  leaf):  said  of  compound  leaves  of  three 

leaflets,  as  in  clover  and  oxalis.     Fig.  259. 
Trimor'phic   or  trimor'phous   (Gr.  tri,   three;    morphe,   form) :    occurring 

under  three  forms,  as  when  the  stamens  and  styles  of  different  flowers 

are  long,  short,  and  intermediate. 
Triter'nate  (L.  tri  +  terni,  by  threes)  :  occurring  in  groups  of  threes  three 

times. 
Tropoph'ilous  (Gr.  trope,  a  turning;  philein,  to  love)  :  adapted  to  change 

of  condition,  such  as  deciduous  trees,  or  plants  whose  above-ground  parts 

die  away  on  the  approach  of  winter  or  dry  season. 
Trop'ophyte  (Gr.  trope  -f  phyton,  plant)  :    plant  which    sheds  its  leaves  or 

whose   above-ground   parts   die   away   on   approach   of    winter   or   dry 

season. 
Trun'cate  (L.  truncatus,  shortened)  :  ending  abruptly.     Fig.  252. 


Glossary.  427 


Tu'ber  (L.  tuber,  a  protuberance  or  tumor)  :  a  short  and  thick  underground 
stem  beset  with  numerous  "  eyes,"  like  the  potato.  Fig.  205. 

Tu'bercle  (L.  tuberculutn,  diminutive  of  tuber)  :  a  small,  knob-like  outgrowth 
such  as  occurs  on  the  roots  of  Leguminosae  for  the  habitation  of  nitrify- 
ing bacteria.  Fig.  13.  Tuber'culate :  beset  with  tubercles. 

Tuberif'erous  (L.  tuber  -\-ferre,  to  bear)  :  tuber-bearing. 

Tu'berous  :  producing  or  resembling  tubers. 

Tu'berous  root:  a  root  thickened  and  tuber-like.     Figs.  217  and  218. 

Tuft'ed  :  growing  in  clusters  or  clumps. 

Tumes'cent:   (L.  tumescens,  swelling  up)  :  somewhat  tumid. 

Tu'mid  (L.  tumidus,  swollen)  :  swollen. 

Tu'nicate  (L.  tunica,  an  under  garment)  :  having  concentric  coats  like  the 
onion. 

Tur'binate  (L.  turbinatus,  cone-shaped)  :  shaped  like  a  top  or  inverted 
cone. 

Tur'gid  (L.  turgidus,  swollen)  :  swollen. 

Um'bel  (L.  umbella,  a  sunshade)  :  a  kind  of  indeterminate  inflorescence 
(older  flowers  toward  the  circumference)  having  the  pedicels  of  the  indi- 
vidual flowers  radiating  from  about  the  same  plane  on  the  common 
peduncle.  Fig.  83,7. 

Um'bellate  :  occurring  in  umbels;  pertaining  to  an  umbel. 

Um'bellet :  a  secondary  umbel. 

Umbelliferous  (L.  umbel  -\-ferre,  to  bear):  producing  or  bearing  umbels. 

Umbel'liform  (L.  umbel  +  forma,  shape)  :  having  the  form  of  an  umbel. 

Unarmed' :  destitute  of  prickles  and  the  like. 

Un'dulate  (L.  undulatus,  wavy)  :  with  a  wavy  surface  or  margin;  repand. 
Fig.  232. 

Une'qual :  applied  to  stamens  of  diverse  lengths. 

Unguic'ulate  (L.  unguis,  a  nail  or  claw)  :  having  a  claw  or  a  narrow,  stalk- 
like  base. 

Uni-  (L.  unus,  one)  :  in  composition  signifying  one  or  single. 

Ur'ceolate  (L.  urceolus,  diminutive  of  urceus,  a  pitcher)  :  hollow  and  cylin- 
drical or  ovoid,  and  more  or  less  contracted  below  the  mouth. 

U'tricle  (L.  utriculus,  diminutive  of  uter,  utris,  a  bag  or  bottle  of  animal 
skin)  :  a  small,  bladder-like  body;  a  small,  thin-walled,  one-seeded  fruit. 
Fig.  326. 

Valv'ate  (L.  valva,  a  wing  or  fold  of  a  folding  door)  :  opening  by  valves; 

joining  at  the  edges  without  overlapping.     Fig.  283. 
Valve  :  one  of  the  parts  into  which  a  dehiscent  capsule  splits. 


428  Introduction  to  Botany. 

Vas'cular  (L.  vasculum,  a  small  vessel)  :  having  vessels  or  ducts  for  the  con- 
duction of  water  and  elaborated  sap. 

Vein :  one  of  the  branching  strands  of  vascular  tissue  in  a  leaf  or  other  organ. 

Ven'tral  (L.  venter,  the  "belly)  :  pertaining  to  the  side  of  a  member  which 
faces  the  axis  from  which  it  springs;  in  floral  organs  the  side  facing  the 
center  of  the  flower ;  the  upper  surface  of  leaves. 

Ven'tricose :  inflated  or  swollen  on  one  side  more  than  on  the  other. 

Ver'nal  (L.  vernalis,  of  or  belonging  to  spring)  :  occurring  in  spring. 

Vernation :  the  arrangement  of  leaves  in  the  bud. 

Verrucose'  (L.  verruca,  a  wart)  :  covered  with  wart-like  elevations. 

Versatile  (L.  versare,  to  turn  round)  :  applied  to  an  anther  which  is  at- 
tached to  the  filament  at  its  center  only  and  may  easily  swing  about,  as  in 
the  tiger  lily.  Fig.  294.  , 

Ver'ticil  (L.  verticillus,  diminutive  of  vertex,  a  whirl,  eddy,  or  whirlpool)  ; 
a  circle  of  leaves  or  flowers  around  a  stem  at  the  same  node.  Fig.  33. 

Vertic'illate :  arranged  in  a  verticil  or  whorl. 

Ves'icle  (L.  vesicula,  diminutive  of  vesica,  a  bladder  or  blister)  :  a  small, 
bladder-like  body  or  cavity. 

Vesic'ular :  composed  of  or  covered  with  vesicles. 

Vexil'lum  (L.  vexillum,  a  banner  or  flag) :  the  upper  petal  of  a  papilio- 
naceous flower;  the  standard.  Fig.  266,  s. 

Vil'lous  (L.  villus,  a  shaggy  hair)  :  bearing  long  and  soft  hairs. 

Vir'gate  (L.  virgatus,  made  of  twigs)  :  wand-shaped,  straight  and  slender. 

Vis'cid  (L.  viscidus,  clammy)  :  sticky  or  clammy. 

Vit'ta,  pi.  vittae  (L.  vitta,  a  band  or  chaplet  worn  round  the  head)  :  an  oil 
tube  found  in  the  carpels  of  the  Umbelliferse. 

Volute'  (L.  valuta,  a  spiral  scroll)  :  rolled  up  in  any  way. 

Whorl,  pr.  hwurl :  an  arrangement  of  leaves  or  floral  organs,  etc.,  around  the 

stem  at  one  plane.     Fig.  33. 

Wild :  growing  spontaneously  without  cultivation. 
Wing:  a  membranous  expansion  of  an  organ  or  member,  an  ala.   The  lateral 

petal  of  a  papilionaceous  corolla.     Fig.  266,  w. 
Woolly:  clothed  with  long,  coiled,  or  matted  hairs. 

Xeroph'ilous  (Gr.  xeros  +  philein,  to  love):   adapted  to  a  dry  climate  or 

habitat. 
Xe'rophyte,  pr.  ze'ro-fite  (Gr.  xeros,  dry;  phyton,  a  plant)  :  a  plant  adapted 

by  its  structure  to  a  dry  habitat. 


INDEX. 


Absorbed  substances,  path  of,  40. 
Absorption,  conditions  affecting,  307 ;  process 

of,  36. 

Accessory  buds,  70. 
Acer,  238. 

Adventitious  buds,  70. 
Adventitious  roots,  44. 
JScidiospores,  281. 
Aerial  plants,  roots  of,  41. 
Agaricus,  282. 
Agave,  142,  821. 
Ailanthus,  213. 
Air  plants,  roots  of,  41. 
Ate,  237. 

Albumen  water,  384. 
Alfalfa,  roots  of,  39. 
Algae,  264 ;  nature  of,  269. 
Alhagi  maurorum,  345. 
Amaryllidaceae,  228. 
Ament,  158. 

Anemone,  147,  180,  207 ;  seeds  of,  213. 
Angular  divergence,  determination  of,  47. 
Annuals,  132. 
Anther,  165. 

Antheridium,  274,  287,  290. 
Ants,  leaf-cutting,  317,  318. 
Archegonia,  287,  288,  290. 
Arctic  regions,  vegetation  in,  342. 
Arisaema  triphyllum,  219. 
Aristolochia,  study  of,  48;  cross  section  of 

stem  of,  49. 
Aristotle,  171. 
Artichoke,  139. 
Asci,  285. 
Asclepias  cornuti,  192,  248;  bee  gathering 

nectar  from,   194;    cross  pollinatiop   of, 

191 ;  diagram  of  flowers  of,  193 ;  seeds  of, 

195,  213. 
Asexual  and  sexual  generations,  comparison 

of,  294. 

Asparagus  medioloides,  136. 
Astragalus  caryocarpus,  287. 
Atmosphere,  818. 
Axillary  buds,  70. 


Bacteria,  cultures  of,  254 ;  disease-producing, 
260;    economic  importance,  260;    forms 


of,  257,  258,  259 ;  nature  of,  256 ;  nitrify- 
ing, 260 ;  nitrogen-fixing,  261 ;  reproduc- 
tion of,  257 ;  staining,  255. 

Balsam,  53. 

Bambusa,  334. 

Banyan,  139 ;  prop  roots  of,  41. 

Barberry,  136,  160. 

Bark,  diagram  of,  58 ;  effect  of  removal  of, 
59. 

Bast,  diagram  of,  58 ;  use  of,  56. 

Batis  maritima,  323. 

Bean,  castor,  8 ;  Lima,  5. 

Bee,  diagram  of  head  of,  186 ;  head  of,  185 ; 
pollen  baskets  of,  186,  187 ;  relation  of,  to 
flowers,  185. 

Beech,  Cretaceous,  355. 

Beggar-ticks,  208,  216. 

Biennials,  132. 

Bittersweet,  207. 

Black  locust,  135. 

Bladderwort,  142,  145, 146. 

Bladder-wrack,  266. 

Bud,  nature  of,  70. 

Budding,  71. 

Buds,  disposition  of  leaves  in,  68 ;  leaf  and 
flower,  69  ;  position  of,  70 ;  summer,  66 ; 
unfolding  of  leaves  of,  68 ;  winter,  66. 

Burdock,  208,  216. 

Burr-grass,  216. 

Butterflies,  relation  of,  to  flowers,  183. 

Butterfly,  diagram  of  head  of,  184 ;  proboscis 
of,  184. 

Cabomba  Caroliniana,  326,  827. 

Cacti,  73  ;  stems  of,  140. 

Cactus,  322. 

Calamites,  853,  854. 

Calcium  oxalate,  occurrence  of,  in  Arisaema, 

220. 

Callitriche  stagnalis,  827. 
Calyptra,  289. 
Calyx,  164. 
Cambium,  50 ;  diagram  of,  58 ;  usefulness  of, 

114. 

Camerarius,  171. 
Capsella  bursa-pastoris,  149,  283. 
Capsules,  of  moss,  286. 


429 


430 


Introduction  to  Botany. 


Carbon  dioxide,  percentage  of,  in  atmosphere, 
93 ;  test  for,  13. 

Carboniferous  plants,  352,  353. 

Cariua,  237. 

Carpels,  201. 

Cassia  chamaecrista,  126. 

Cassiope  tetragona,  328. 

Castor  bean,  168;  experiments  with,  116, 
11T,  118. 

Catalpa,  207,  213. 

Catasetum  tridentatum,  190. 

Caulicle,  7. 

Cecropia  adenopus,  317,  318,  319  ;  food  bodies 
of,  320. 

Cell,  definition  of,  104;  division,  107;  dia- 
gram illustrating  division,  109 ;  growth 
of,  108 ;  organs  of,  105. 

Cells,  changes  in  character  of,  110. 

Cellular  structure,  advantages  of,  107. 

Cellulose,  reserve,  22. 

Central  cylinder,  49. 

Centrifugal  force,  influence  of,  25. 

Ceratophyllum,  79,  305. 

Cereus  ingens,  321 ;  giganteus,  321. 

Chestnut,  Cretaceous,  355. 

Chinese  primrose,  147. 

Chloral  hydrate,  381. 

Chloroiodide  of  zinc,  381. 

Chlorophyll,  87. 

Chloroplasts,  87,  88,  106. 

Chrom-acetic  fixative,  382. 

Chromoplasts,  106. 

Chromosomes,  109. 

Cladonia  furcata,  284. 

Cladophyll,  140. 

Classification  of  plants,  359. 

Clinostat,  how  to  make,  15. 

Clover,  root  tubercles  of,  39. 

Cochlearia  fenestrata,  811. 

Cocklebur,  208,  216. 

Cockroach,  182  ;  diagram  of  eye  of,  183. 

Cocoanut,  seed  and  seedling  of,  23. 

Cocoanut  palm,  335. 

Colchicum,  122. 

Cold,  resistance  to,  810. 

Collecting,  368. 

Collecting  case,  how  to  make,  368. 

Collenchyma,  50. 

Color,  181. 

Composite  flowers,  method  of  diagraming, 
155. 

Compound  eye,  182. 

Conceptacle,  266,  275. 

Conduction,  57. 

Continuity  of  living  substance,  107. 

Cordiates,  352,  353,  854. 

Corn,  Indian ,  10 ;  prop  roots  of,  41. 


Corolla,  164 ;  ligulate,  155 ;  tubular,  155. 
Corpusculum,  193, 195. 
Corydalis,  233. 
Corymb,  159. 

Cottonwood,  67,  68,  207 ;  buds  of,  69 ;  dis- 
persal of  seeds  of,  213,  214. 
Cotyledons,  6,  7. 
Crab  apple,  207. 

Cranesbill,  elastic  carpels  of,  210. 
Cretaceous  period,  equable  climate  in,  855. 
Crocus,  122. 

Cross  fertilization,  170 ;  devices  for,  175. 
Cuscuta,  139 ;  roots  of,  44. 
Cutin,  56. 
Cuttage,  44. 

Cutting  sections,  376,  377,  382,  383. 
Cyanin  and  erythrosin,  384. 
Cycads,  354,  355. 

Cypripedium  pubescens,  227 ;  insigne,  229. 
Cytoplasm,  105 ;  functions  of,  106. 

Dahlia,  72. 

Dandelion,  208. 

Darlingtonia,  143,  144. 

Darwin,  170. 

Date,  seed  and  seedling  of,  28. 

Datura,  cross  pollination  of,  187. 

Deliquescent  trunk,  66. 

Delphinium,  231. 

Dendrocalamus,  334,  335. 

Desert  regions,  cause  of,  346;  rainfall  of, 
346 ;  vegetation  of,  345. 

Determinate  inflorescence,  159. 

Devonian  plants,  352. 

Diagrams,  floral,  152. 

Diagrams  of  leaves,  flowers,  inflorescences, 
158,  159. 

Dicentra  cucullaria,  232. 

Dichogamous,  176. 

Dicotyledons,  first  appearance  of,  355;  re- 
gions of  growth  in,  110. 

Diffusion,  nature  of,  36. 

Digestion,  21. 

Dimorphic,  176. 

Dioecious,  175. 

Dionaea  muscipula,  127. 

Dispersion  by  animals,  215;  birds,  215; 
elastic  tissues,  210  ;  water,  216  ;  winds, 
211. 

Dispersion  of  fruits  and  seeds,  207 ;  impor- 
tance of,  208. 

Dissecting  needles,  how  to  make,  372. 

Dissecting  stands,  how  to  make,  871. 

Distribution,  original,  of  plants,  328. 

Division  of  cells,  107. 

Dodder,  41 ;  roots  of,  30. 

Dogbane,  208. 


Index. 


43 


Double  staining,  384. 

Drawing,  1 ;  procedure  in,  2 ;  rules  for,  2. 

Drosera  rotundifolia,  127,  128. 

Egg,  164,  167 ;  fertilization  of,  167,  168. 

Elder  pith,  inclosing  objects  in,  377. 

Elements  necessary  to  plants,  38. 

Elm,  208 ;  Cretaceous,  355 ;  dispersal  of  seeds 
of,  213. 

Embryo,  7 ;  condition  of,  in  seed,  18 ;  forma- 
tion of,  299. 

Embryology  of  flower,  205. 

Embryo  sac,  165,  167,  203. 

Embryo  sac  spore,  behavior  of,  298. 

Endodermis,  49. 

Endosperm,  168. 

Energy,  source  of,  84;  source  of  internal, 
131. 

Environment,  adaptation  to,  303;  result  of 
unfit,  304. 

Environmental  factors,  most  potent,  319. 

Epicotyl,  7. 

Epidermis,  48 ;  function  of,  50,  56. 

Epigynous,  205,  206. 

Equisetum,  355 ;  arvense,  301. 

Erigeron,  250. 

Erythronium,  albidum,  221;  Americanum, 
221 ;  dens-canis,  222 ;  mesachorium,  222. 

Euphorbia,  210 ;  serpens,  73. 

Evergreens,  leaves  of,  97. 

Excurrent  trunk,  67. 

Family,  361. 

Fascicle,  159. 

Feathergrass,  208. 

Fehling's  solution,  385. 

Ferments,  21 ;   position  of,  22 ;  removal  of 

products  of,  23. 
Fern,  diagram  of  sphorophyte  and  gameto- 

phyte  of,  295. 
Ferns,  286;  antheridium  and  archegonium 

of,  293;  character  of,  292;  gametophyte 

of,  293;  prothallium  of,  293;  rhizbids  of, 

294 ;  sperms  of,  293. 
Fertilization,  process  of,  166 ;  result  of,  168 ; 

time  required  for,  169. 
Field  work,  4. 
Filament,  165. 
Fixative,  chrom-acetic,  382. 
Floral  diagrams,  152,  154,  155,  156. 
Floras,  factors  governing,  328. 
Flower  buds,  69. 
Flower,   embryology   of,  205;    longitudinal 

diagram  of,  165 ;  morphology  of,  201. 
Flowers,  guide  for  drawing,  150. 
Food,  character  and  location  of,  In  seeds,  18 ; 

demonstration  of  value  of,  14 ;  reserve,  12. 


Forces,  influence  of  various,  122. 

Fragaria,  363  ;  virginiana,  235. 

Fragrance,  181. 

Freesia,  147. 

Fucus,  vesiculosus,  266,  275;    reproduction 

of,  275. 
Fungi,  264 ;  character  of,  277 ;   ravages  of, 

283 ;  saprophytic,  277. 
Funiculus,  165. 

Gametophyte,  294-300;  of  mosses,  291, 

Genera,  360. 

Genus,  361. 

Geranium,  207 ;  sylvaticum,  172. 

Germination,  completion  of,  27;  necessary 
conditions  for,  20 ;  time  of,  19. 

Gingko,  354. 

Girdling,  advantage  of,  59 ;  effect  of,  59  ;  pro- 
cess of,  54. 

Glomerule,  159. 

Glucose,  test  for,  12. 

Glycerine  jelly,  385. 

Goldenrod,  72,  73,  140,  208. 

Gooseberry,  207. 

Grafting,  72. 

Grape  sugar,  test  for,  12. 

Grape  vine,  rise  of  sap  in,  31. 

Graphis  scripta,  284. 

Grasses,  111 ;  tertiary,  356. 

Gravity,  as  directive  force,  43;  as  guide  to 
growth,  61 ;  influence  of,  24, 114 ;  to  elimi- 
nate effect  of,  16 ;  neutralizing  influence 
of,  25. 

Ground  tissue,  53. 

Growth,  apparatus  for  measuring,  101 ;  con- 
ditions necessary  to,  112;  diagram  illus- 
trating, 111 ;  direction  of,  23,  61 ;  nature 
of,  133  ;  phases  of,  112  ;  rings  of  annual, 
114 ;  regions  of  continued,  110. 

Growth  of  cells,  108. 

Gymnosperms,  early  representatives  of,  354. 

Habitats,  kinds  of,  305. 

Habits  of  stems,  73. 

Halophytes,  319  ;  character  of,  323 ;  origin  of, 

326. 

Halophytic  conditions,  820. 
Hazelnut,  207. 
Head,  159. 

Heat,  resistance  to,  812. 
Helianthemum  vulgare,  850,  364. 
Heliotropism,  120 ;  definition  of,  122. 
Herbarium,    character    of,    867 ;     preparing 

specimens  for,  868. 
Hickory,  67,  68. 
Hilum,  7. 
Honey  glands,  148. 


43  2 


Introduction  to  Botany. 


Honey  locust,  135. 

Honeysuckle,  147. 

Hop  hornbeam,  207. 

Hornbeam,  207. 

Horse-chestnut,  67,  68,  82 ;  study  of,  45. 

Horsetails,  286,  300,  353 ;  prothallia  of,  301 ; 

reproduction  of,  300. 
Hyacinth,  147,  206,  223. 
Hydrophytes,  319 ;  character  of,  323 ;  origin  of, 

326 ;  most  general  characteristics  of,  326. 
Hydrophytic  conditions,  320. 
Hydrotropism,  diagram  illustrating,  102. 
Hypocotyl,  7. 
Hypogynous,  204,  205. 
Hypoxis  erecta,  223. 

Imbedding  in  paraffin,  386. 

Indeterminate  inflorescence,  159. 

Indian  corn,  168 ;  constitution  of  stem  of,  52 ; 

cross  section  of  stem  of,  52 ;  inflorescence 

of,  177  ;  stem  of,  59. 
Insects,  adaptations  to,  179 ;  sense  of  sight 

of,  182  ;  sense  of  smell  of,  182. 
Internal  energy,  source  of,  181. 
Internodes,  66. 
Iodine  solution,  387. 
Ipomcea,  812  ;  leptophylla,  138. 
Iridaceae,  228. 
Iris,  175 ;  germanica,  224 ;  xiphium,  225. 

Jimson-weed,  cross  pollination  of,  187. 

Keel,  237. 
Koalreuter,  171. 

Lahore,  maximum  temperature  at,  312. 

Larkspur,  147,  154,  207. 

Layering,  method  of,  44. 

Leaf  bud,  69. 

Leaf,  cross  section  of,  88  ;  diagram  of  essen- 
tial parts  of,  89  ;  summary  of  functions  of, 
99  ;  work  done  by,  85,  and  pages  following. 

Leaves,  amount  of  work  done  by,  96 ;  char- 
acterization of,  98 ;  continued  growth  of, 
112  ;  disposition  of,  in  buds,  68 ;  duration 
of,  96  ;  formation  of,  66 ;  guides  for  draw- 
ing, 150 ;  lifting  power  in,  61 ;  light  rela- 
tion of,  82  ;  modified,  142  ;  position  of,  81 ; 
prominence  of,  81 ;  relation  of,  to  roots,  99  ; 
significance  of  definite  arrangement  of,  82 ; 
size  and  form  of,  97. 

Lemna,  40. 

Lenses,  how  to  use,  372 ;  care  of,  873. 

Lenticels,  93. 

Lepidodendrons,  353,  354. 

Leucoplasts,  105,  106. 

Lichens,  264  ;  nature  of,  284. 


Life,  length  of,  183. 

Light,  308 ;  as  guide  to  growth,  63  ;  effect  of 
dim,  308;  effect  of  intense,  309  ;  influence 
of,  114 ;  in  temperate  regions,  342  ;  nature 
of,  84. 

Ligulate  corolla,  155. 

Lilac,  82. 

Liliaceaj,  228. 

Lima  bean,  168  ;  study  of,  5. 

Lime  water,  387 ;  use  of,  IS. 

Linaria  cymballaria,  65. 

Living  substance,  continuity  of,  107. 

Lycopodium,  202,  204. 

Lycopods,  353. 

Macrosporangium,  203. 

Macrospore,  203. 

Macrosporophyll,  203. 

Maple,  207,  208 ;  Cretaceous,  355. 

Materials,  conduction  of,  57. 

Medullary  rays,  49 ;  diagram  of,  58,  60 ;  func- 
tion of,  51 ;  movement  in,  60. 

Melilotus  alba,  cross  sections  of  leaf  of,  90,  91. 

Mentzelia,  216. 

Mesembryanthemum,  142,  322. 

Micropyle,  7,  165,  167. 

Microscope,  compound,  373,  374;  diagram  of 
compound,  374 ;  how  to  use,  872,  373,  374, 
375 ;  simple,  371. 

Microsporangium,  203. 

Microspore,  203. 

Microsporophyll,  203. 

Microtome,  method  of  using  simple,  878. 

Migration,  17;  by  seeds,  209. 

Mildews,  264. 

Milkweed,  207,  208. 

Mimosa  pudica,  124, 126 ;  preparing  seedlings 
of,  100. 

Mistletoe,  41. 

Modified  leaves,  142. 

Modified  roots,  188. 

Modified  stems,  139. 

Monocotyledons,  regions  of  continued  growth 
in,  110  ;  time  of  appearance  of,  355. 

Monoecious,  175. 

Morning  glory,  184. 

Morphological  elements,  134,  136 ;  character- 
istics of,  138. 

Moss,  diagram  of  sporophyte  and  gameto- 
phyte  of,  296. 

Mosses,  dissemination  of  spores  of,  291 ; 
gametophyte  of,  296 ;  illustration  of,  289  ; 
reproduction  of,  290 ;  sexual  and  asexual 
generations  of.  291 ;  sporophyte  of,  291. 

Motor  organs,  122. 

Mountain  heights,  physical  conditions  of, 
847 ;  vegetation  of,  347. 


Index. 


433 


Mounting  sections,  383. 

Movements,    causes  of,   120;    spontaneous, 

129. 
Mucor  mucedo,  27T,  278;    reproduction  of, 

277. 

Mucor  stolonifer,  277. 
Multan,  maximum  temperature  at,  312. 
Multiplication,  17. 
Myosotis  palustris,  173. 
Myosurus,  231. 
Myriophyllum,  79,  305. 
Myxomycete,  252 ;   formation  of  spores  of, 

253. 

Naias  flexilis,  218. 

Nasturtium,  181. 

Nectar,  180, 181 ;  allurement  by,  180 ;  glands, 

143 ;  receptacle,  180. 
Nelumbo,  140. 
Nelumbo  lutea,  324 ;  dispersion  of  seeds  of, 

216. 

Nemastylis,  227. 
Nematophyton,  352. 
Nepenthes,  142,  143. 

Nitrogen,  how  obtained  by  plants,  38, 39,  260. 
Nodes,  66. 
Nucellus,  165. 
Nucleus,  105 ;  functions  of,  106 ;  as  bearer  of 

inheritable  qualities,  168. 
Nymphaea  odorata,  204. 

Oak,  Cretaceous,  355;  reserve  materials  in 

cotyledons  of,  27. 
(Edogonium,  163,  164,  166,  264. 
(Enothera  Missouriensis,  330 ;  laciniata,  330 ; 

rhombipetala,  330 ;  speciosa,  247. 
Onion,  preparing  root  tips  of,  100. 
Oogonium,  163,  274. 
Operculum,  291. 
Orange,  208. 
Orchidaceae,  228. 

Orchids,  cross  pollination  of,  190  ;  roots  of,  41. 
Order,  361. 

Organs  of  the  cell,  105. 
Osage  orange,  135. 
Osmosis,  37. 

Osmotic  pressure,  60,  61. 
Ovary,  165. 
Ovule,  165. 

Oxalis,  148,  207  ;  stricta,  238 ;  violacea,  238. 
Oxidation  a  vital  process,  132. 
Oxygen,  evolution  of,  91 ;  necessity  of,  in 

germination  of  seeds,  15,  21. 

Palisade  cells,  88. 

Palm,   111;    Cretaceous,  355;    stem  of,  59; 
Sabal,  339  ;  trees,  335. 


Pappus,  156. 

Paraffin,  imbedding  in,  386;  oven,  how  to 

make  simple,  386;  sections,  cutting  and 

mounting,  383. 
Parasitic  plants,  roots  of,  40. 
Parmelia  colpodes,  284. 
Parmentiera  cereifera,  337. 
Pencils,  colored,  use  of,  3 ;  how  to  sharpen,  2. 
Perennials,  132. 
Pericycle,  49 ;  function  of,  51. 
Perigynous,  204,  205,  206. 
Permian  plants,  354. 
Petal,  164. 
Petunia,  184. 
Phloem,  diagram  to  show,  58,  91 ;  function 

of,  51. 

Phloroglucin,  387. 

Photosynthesis,  92 ;  essential  nature  of,  132. 
Pine,  177,  208;    pistillate  inflorescence    of, 

178 ;  staminate  catkin  of,  177. 
Pines,  339. 
Pistil,  165,  203 ;  compound,  204 ;  half  inferior, 

204 ;  inferior,  205 ;  simple,  203 ;  superior, 

204. 

Pistillate,  175. 
Pitcher  plants,  142. 
Pith,  49;   elder,  inclosing  objects  in,  377; 

function  of,  51. 
Plant  forms,  diversity  of,  136. 
Plants,  antiquity  of,  351;   classification  of, 

359  ;  Carboniferous,  352 ;  Cretaceous,  355 ; 

Devonian,   352;    Jurassic,  355;    of  past 

ages,  351 ;  Permian,  354 ;  Tertiary,  356. 
Plasma  membrane,  105 ;  function  of,  105. 
Plasmodium,   streaming  of  protoplasm  in, 

104. 

Plastids,  106. 

Pleurococcus,  264,  284 ;  viridis,  270. 
Pliny,  171. 

Plum,  135,  207 ;  diagram  of  flower  of,  206. 
Plumule,  7. 
Poison  ivy,  138. 

Pollen,  allurement  by,  180 ;  of  pine,  177. 
Pollen  grain,  165. 
Pollen  tube,  165, 167,  169. 
Pollinium,  190, 192, 197. 
Poplar,  177. 

Poplars,  Cretaceous,  355. 
Poppy,  180. 

Populus  monilifera,  213,  230. 
Portulacca,  322. 
Potato,  73,  136,139. 
Preparing  materials  for  herbarium,  368. 
Prickly  ash,  135. 

Primary  cortex,  49  ;  function  of,  50. 
Primitive  physical  conditions,  351, 
Primula,  176. 


434 


Introduction  to   Botany. 


Pronuba  moth,  196-201. 

Protective  adaptations,  31T. 

Proteid,  test  for,  12. 

Proteids,  96 ;  manufacture  of,  91. 

Proterandrous,  176. 

Proterogynous,  1T6. 

Prothallia,  288. 

Prothallium,  208. 

Protonema,  287. 

Protoplasm,  streaming  of,  103. 

Protoplast,  105 ;  sensibility  of,  118. 

Prunus  chicasa,  234. 

Puccinia,  280. 

Quaternary,  exodus  southward  in,  356 ;  north- 
ward migration  in,  858. 
Quercus  virens,  841. 

Eaceme,  158. 

Eaces,  361. 

Eadicle,  7. 

Eainfall,  effect  of  annual,  840. 

Eainfall  map,  332,  833. 

Eanunculus,  147 ;  abortivus,  231 ;  fluitans, 
325,  327. 

Eaphia  tsedigera,  97. 

Eaw  materials,  supply  of,  93. 

Eeagents,  881 ;  applying,  878. 

Eeceptacle,  165,  166. 

Eelationship,  best  evidence  of,  864. 

Eeproduction,  different  methods  of,  162 ; 
relative  values  of  asexual  and  sexual,  169. 

Eeserve  materials,  circulation  of,  21 ;  loca- 
tion of,  in  stems,  etc.,  69. 

Eespiration,  92 ;  essential  process  of,  181. 

Eesting  spore,  168. 

Ehizoid,  289. 

Ehododendrons,  Cretaceous,  855. 

Eing  leaf,  205. 

Eings  of  annual  growth,  114;  constitution 
of,  115. 

Eoot  hairs,  26 ;  action  of,  35 ;  importance  of, 
33 ;  relation  of,  to  water-conducting  tubes, 
40  ;  structure  of,  35. 

Eoots,  adventitious,  44 ;  aerial,  41 ;  clinging, 
48;  definition  of,  44;  demonstration  of 
erosive  action  of,  28 ;  demonstration  of 
region  of  growth  of,  30 ;  directive  forces 
affecting,  43 ;  early  formation  of,  26 ;  ex- 
tent of,  39 ;  force  of  absorption  by,  29 ; 
functions  of,  31 ;  modified,  138 ;  necessary 
substances  absorbed  by,  99  ;  parasitic,  40  ; 
prop,  41 ;  region  of  growth  of,  30 ;  relation 
of,  to  leaves,  99  ;  of  water  plants,  40. 

Eosa  Arkansana,  236. 

Bose,  180,  207 ;  diagram  of  flower  of,  206. 


Eubus  hispidus,  362,  368. 
Eubus  villosus,  361,  863. 
Euscus,  140,  141. 
Eusts,  264,  279. 

Safranin,  888. 

Sagittaria,  62,  73. 

Sahara,  vegetation  of,  346. 

Salix,  229  ;  polaris,  344. 

Salts,  effect  of  excess  of,  315. 

Salvia,  cross  pollination  of,  188. 

Saprophytic  fungi,  277. 

Sarcobatus  baileyi,  346. 

Sarracenia*variolaris,  144. 

Sassafras,  Cretaceous,  355. 

Scape,  219. 

Scarlet  runner,  128. 

Sclerenchyma  ring,  50. 

Scolopendrium,  292 ;  officinarum,  809. 

Sealing  in  balsam,  388. 

Section  cutting,  376,  382,  388. 

Sedum,  142. 

Seed-coats,  6. 

Seed  dispersion,  importance  of,  208. 

Seedlings,  providing  for  students'  use,  5. 

Seed,  protection  of,  18. 

Seeds,  dispersion  of,  by  birds  and  other  ani- 
mals, 215 ;  by  elastic  tissues,  210 ;  by 
winds,  211 ;  various  devices  for  dispersion 
of,  212 ;  importance  of  dispersion  of,  208  ; 
method  of  planting,  5 ;  migration  by,  209  ; 
multiplication  and  migration  by,  17 ; 
nature  and  purposes  of,  16 ;  size  of,  27. 

Selaginella,  202,  203,  204. 

Self  fertilization,  170. 

Sempervivum  tectorum,  309. 

Sensitive  plant,  124,  125,  126. 

Sepal,  164. 

Sequoia,  355 ;  distribution  of,  in  Cretaceous 
period,  355 ;  extermination  of,  in  Europe 
and  Asia,  356 ;  photograph  of,  857. 

Sexual  and  asexual  generations,  comparison 
of,  294. 

Sharpening  knives,  etc.,  378,  879. 

Shoot,  upward  growth  of,  55. 

Shrankia  uncinata,  126. 

Siberian  forests,  810. 

Sicyos  angulatus,  316. 

Sieve  tubes,  59  ;  movement  in,  61. 

Sigillarias,  353,  354. 

Sisyrinchium,  224,  227. 

Slime  moulds,  251 ;  formation  of  spores  of, 
253  ;  nature  of,  252. 

Smilax,  111,  134;  chloroplasts  in,  809. 

Smuts,  264. 

Snakeroot,  208,  216. 

Soil,  315  ;  effect  of  character  of,  330 ;  forma- 


Index. 


435 


tion  of,  34 ;  nature  of,  33 ;  as  reservoir  for 

water,  34. 

Solanum  jasminoides,  137, 142. 
Soldanelias,  312,  313. 
Solomon's  seal,  72;  diagram  of  flower  of, 

206. 

Sorus,  288. 
Spadix,  219. 
Spathe,  219. 
Species,  360. 
Sperm,  164,  167. 

Spermatophytes,  asexual  and  sexual  genera- 
tions of,  294,  297,  299 ;  studies  of  selected, 

218. 

Sphinx  moth,  182  ;  and  Datura  flower,  188. 
Spike,  158. 
Spirodela,  40. 

Spirogyra,  264 ;  reproduction  of,  272. 
Spongy  parenchyma,  88. 
Spontaneous  movements,  129. 
Sporangia,  202. 
Sporophyll,  202,  203,  300. 
Sporophyte,  294-300;  of  moss,  289,  291. 
Sprengel,  171. 
Spurge,  207. 
Squash,  tendrils  of,  103. 
Squirting  cucumber,  211. 
Staining  paraffin  sections,  388. 
Stamen,  165.          , 
Stamens,  201. 
Staininate,  175. 
Standard,  237. 
Starch,  96;   formation  of,  87;   sheath,  49; 

test  for,  12. 
Stele,  49. 
Stem,  chief  function  of,  55 ;  diagram  of,  58 ; 

summary  of  functions  of,  60. 
Stems,  characterization  of,  74 ;  functions  of, 

72  ;  habits  of,  73 ;  modified,  139. 
Stigma,  165. 
Stigmatic  chamber,  193. 
Stigmatic  disk,  192. 
Stimulus,  transmission  of,  126. 
Stomata,  86 ;  action  of,  94 ;  determination  of 

necessity  of,  80. 
Strawberry,  207. 
Streaming  of  protoplasm,  108. 
Strengthening  elements,  56. 
Study,  method  of,  1. 
Style,  165. 

Sugar,  grape,  test  for,  12. 
Sumac,  207. 
Sundew,  128. 

Sunflower,  heliotropism  of,  121. 
Superior  pistil,  204,  205. 
Sweet  alyssvum,  147. 
Syngenesious  stamens,  155. 


Tabernsemontana  dichotama,  388. 

Tables  for  laboratory,  371. 

Taraxacum  officinale,  248. 

Taxodium,  133. 

Taxus,  133. 

Tecoma  radicans,  65. 

Teleutospores,  280. 

Temperate  regions,  light  in,  342 ;  rainfall  of, 
338,  340 ;  temperature  of,  338,  340 ;  vege- 
tation in,  338. 

Temperature,  310. 

Terminal  buds,  70. 

Testa,  6. 

Theophrastus,  171. 

TUlandsia  usueoides,  840,  841. 

Timber  line,  348,  349. 

Toadstools,  281. 

Touch-me-not,  211. 

Tracheal  tubes,  57 ;  diagram  of,  58. 

Tradescantia,  study  of  hairs  of,  100,  103. 

Translocation,  diagram  to  show,  99. 

Transpiration,  91. 

Transplanting,  time  for,  33. 

Transporting  forces,  60. 

Tree  claims,  329,  330. 

Triassic  plants,  354. 

Trimorphic,  176. 

Triteleia,  147. 

Tropical  forest,  336. 

Tropics,  mean  temperature  of,  831;  rainfall 
of,  331 ;  vegetation  in,  331,  334. 

Trumpet  creeper,  65,  103,  138,  213 ;  clinging 
roots  of,  43. 

Tubercles  on  roots,  38. 

Tubular  corolla,  155. 

Tulip,  122,  223. 

Twining,  method  of,  130 ;  benefit  of,  131. 

Twining  plants,  130. 


Ulothrix  zonata,  162. 
Umbel,  159. 
Uredospores,  280. 
Utricularia,  134,  186,  145: 


Vallisneria,  179, 180. 
Variation,  cause  of,  360. 
Varieties,  361. 

Vascular  bundle,  49 ;  diagram  of,  49 ;  func- 
tion of,  51 ;  position  of,  in  leaves,  88. 
Vaucheria,  264,  273. 
Vega  expedition,  310. 
Venus's  flytrap,  127. 
Vexillum,  237. 
Viola,  239-247. 
Violet,  154,  180,  207. 


43  6 


Introduction  to  Botany. 


Virginia  creeper,  73, 136 ;  effect  of  darkness 
on,  118 ;  experiment  with  tendrils  of,  103. 
Viscid  disk,  190. 

Walnut,  20T. 

Water,  cross  pollination  by,  178 ;  demonstra- 
tion of  region  of  rise  of,  29,  53 ;  current, 
diagram  to  show,  99 ;  effect  of  submerg- 
ence in,  807 ;  importance  of,  87 ;  effect  of 
scarcity  of,  306. 

Water  lily,  140. 

Water  plants,  roots  of,  40. 

Water  supply,  306. 

Wild  cucumber,  tendrils  of,  103. 

Willow,  177 ;  adventitious  roots  of,  44 ;  Cre- 
taceous, 355. 

Wind,  adaptation  to,  177. 

Winds,  effect  of,  814. 


Winter  buds,  protection  afforded,  67. 
Wood,  use  of,  56. 

Xerophytes,  319 ;   character  of,  322 ;  North 

American,  321 ;  origin  of,  326. 
Xerophytic  conditions,  320. 
Xylem,  diagram  to  show,  58,  91 ;  function  of, 

51. 

Yeast,  culture  of,  256 ;  in  alcoholic  fermenta- 
tion, 263  ;  in  bread-making,  262 ;  nature 
of,  261 ;  reproduction  of,  262.  ; 

Yucca,  147 ;  arboreus,  321 ;  cross  pollination 
of,  196-201 ;  in  twilight,  198. 

Zilla  spinosa,  845. 

Zygophyllum  cornutum,  322,  328. 


INTRODUCTION    TO    BOTANY 


KEY   AND   FLORA 


BY 

WILLIAM  CHASE  STEVENS 

PROFESSOR   OF   BOTANY   IN   THE   UNIVERSITY   OF   KANSAS 


BOSTON,   U.S.A. 

D.   C.   HEATH    &   CO.,   PUBLISHERS 
1902 


COPYRIGHT,  1902, 
BY  D.  C.  HEATH  &  Co. 


PRINTED   IN 

UNITED    STATES 

OF   AMERICA 


MANNER   OF   USING    THE   KEY   AND    FLORA. 


THE  manner  of  using  the  Key  and  Flora  in  finding  the  names  of  plants 
will  best  be  learned  by  following  a  few  examples.  Since  the  Dogtooth  Violet 
is  one  of  the  first  to  bloom  in  the  spring,  we  will  begin  with  it. 

Turn  to  the  Key  on  page  7,  and  begin  with  Class  I.  Since  our  plant  has 
its  ovules  inclosed  in  an  ovary,  it  can  not  be  found  under  this  class,  in  which 
the  plants  (such  as  firs,  pines,  spruces,  etc.)  have  naked  ovules.  (See  Bot- 
any, page  177,  par.  127,  and  Figs.  93  and  94.) 

But  under  Class  II  we  find  the  ovules  inclosed  in  an  ovary,  and  we  see  at 
a  glance  that  our  plant  belongs  here  under  Subclass  I,  since  the  parts  of  the 
flower  are  in  whorls  of  three,  and  the  leaves  are  parallel  veined.  (Compare 
with  Subclass  II  at  the  bottom  of  the  page.)  Now  read  after  A,  and  if  the 
terms  are  not  understood,  look  them  up  in  the  Glossary  (Botany,  pages  399- 
428).  Clearly  our  plant  has  a  corolla,  and  can  not  come  under  A.  Reading 
next  after  B,  we  note  that  the  flowers  of  our  plant  are  not  on  a  spadix  and 
are  provided  with  two  whorls  of  floral  envelopes  which  may  be  considered  as 
calyx  and  corolla,  and  we  accordingly  look  for  it  under  B.  (Read  after  C,  to 
be  sure  that  it  could  not  belong  there.) 

Under  B  are  three  lines  beginning  with  "  Perianth,"  and  we  see  that  our 
plant  belongs  under  the  second  of  these,  which  reads,  "  Perianth,  wholly  free 
from  the  ovary,"  etc. 

Thus  we  are  brought  to  the  Liliaceae,  page  19,  and  we  turn  directly  to  that 
page  and  read  the  description  of  the  family,  and  finding  that  our  plant  con- 
forms to  it,  we  follow  the  key  to  the  family  to  find  the  genus  to  which  our 
plant  belongs.  Evidently  we  must  hunt  at  once  under  the  line  "  Not  woody 
climbers."  The  flowers  of  our  plant  are  not  umbellate,  nor  borne  in  racemes 
or  spikes,  and  so  we  pass  at  once  to  the  third  line,  beginning  "  Flowers." 
Reading  under  this  line  we  find,  "  Stems  leafy  only  at  the  base;  flowers  single 
and  erect."  But  our  flower  is  not  erect,  and  so  we  pass  to  the  next  line, 
where  the  flower  is  said  to  be  nodding.  This  is  true  of  our  flower,  and  it  is 
evidently  to  be  looked  for  under  Genus  VII,  Erythronium. 

We  read  the  description  of  this  genus  on  page  22,  and  find  that  our  plant 
belongs  there.  We  next  read  the  description  of  the  two  species  there  given 
to  determine  to  which  of  these  our  Dogtooth  Violet  may  belong. 

Let  us  take  for  our  next  example  the  Maple,  which  also  blooms  early  in 
the  spring.  Turn  again  to  the  Key  on  page  7.  Clearly  the  maple  belongs  in 
Class  II;  and  under  this  we  find  that  we  can  pass  directly  to  Subclass  II, 
since  the  stem  of  the  maple  has  distinct  zones  of  bark,  wood,  and  pith,  and 
the  calyx  (the  corolla  is  absent  in  the  maple)  is  4-5  lobed  or  parted. 

Under  Subclass  II,  on  pages  8,  9,  and  10,  we  find  three  main  divisions, 
headed  with  A,  B,  and  C.  After  A  we  read,  "  Corolla,  and  sometimes  calyx, 
wanting,"  while  in  the  other  divisions  both  calyx  and  corolla  are  present. 
Since  the  corolla  is  lacking  in  the  maple,  we  must  look  for  it  under  A.  Here 

3 


4  Using  the  Key  and  Flora. 

we  find  two  large  groups,  one  having  "  flowers  monoecious  or  dioecious,  stami- 
nate  and  sometimes  pistillate,  flowers  in  catkins,"  and  the  other  having 
"  flowers  not  in  catkins."  The  maple,  of  course,  belongs  under  the  latter. 
Here  we  find  two  main  groups,  headed,  "Pistil  more  than  I,"  etc.,  and 
"Pistil  I,"  etc.  Our  plant  belongs  under  the  latter,  where  the  plants  are 
grouped  as  "  herbs,"  or  "  shrubs  and  trees."  The  maple  being  a  tree,  we 
proceed  under  the  latter  heading. 

The  maple  has  a  pair  of  ovules  in  each  cell  of  the  ovary,  and  the  fruit  is  a 
double  samara,  and  we  accordingly  find  th*at  we  must  look  for  it  in  the  genus 
Acer,  in  the  family  Sapindaceae,  on  page  74.  Having  traced  a  plant  to  its 
family  (in  this  case  the  Key  directed  us  at  once  to  the  genus),  it  is  a  good 
plan  to  read  the  description  of  the  family,  to  make  certain  that  the  plant  has 
been  rightly  traced.  Now  read  the  description  of  the  genus,  Acer,  and  of  the 
species  under  it,  and  determine  to  which  one  of  these  our  maple  belongs. 

As  a  final  example  we  will  trace  the  single-flowered  Sweet  Alyssum  of  the 
greenhouses.  Beginning  with  the  Key  on  page  7,  as  oefore,  we  find  our 
plant  goes  to  Subclass  II.,  and  under  this  to  division  B  on  page  8.  Under  B 
we  find  three  main  groups,  numbered  (i),  (2),  and  (3),  depending  on  the 
number  of  stamens.  Our  plant  must  be  under  (3),  "  Stamens  not  more  than 
twice  as  many  as  the  petals,"  etc.  Under  this  division  we  find  two  chief 
groups,  designated  by  (a),  "Ovary  superior,"  etc.,  and  (£),  "Ovary  inferior," 
etc.  (on  page  10).  Clearly  our  plant  comes  under  (#).  Here  we  find  four 
groups,  depending  on  the  number  and  character  of  the  pistils.  Our  plant 
goes  to  the  last  of  these,  "Pistil  I,  compound,  as  shown  by  the  number  of 
cells,  placentae,  styles,  or  stigmas."  (Read  about  compound  pistils  on  pages 
203  and  204  of  the  Botany.) 

In  alyssum  we  conclude  that  two  carpels  compose  the  pistil,  because  there 
are  two  cells,  each  having  a  row  of  ovules;  thus  indicating  two  placentae  and 
two  carpels.  A  pistil  may  be  one-celled  and  still  be  compound  as  indicated 
by  the  placentae  or  rows  of  ovules.  The  violets  afford  a  good  example  of  this. 

Under  "  Pistil  I,  compound,"  etc.,  there  are  two  groups,  one  having  the 
"  ovary  I -celled,"  and  the  other  with  "ovaries  2  or  more  celled."  Our  plant 
comes  under  the  latter,  and  under  "  Flowers  nearly  or  quite  regular  " ;  and 
since  the  stamens  of  alyssum  are  tetradynamous,  we  find  that  we  must  look 
for  it  under  the  family  Cruciferae,  page  47. 

Following  the  Key  to  the  family,  we  find  we  are  led  to  Division  II,  under 
"  Flowers,  white  " ;  and  since  the  pods  of  our  plant  become  orbicular,  we  are 
taken  to  Genus  XIV,  Alyssum,  We  now  turn  the  pages  of  the  family  until 
we  find  this  genus  (on  page  53). 

When  only  a  few  genera  have  been  given  under  a  family,  a  key  to  the 
family  is  not  given,  and  the  proper  genus  is  to  be  determined  by  reading  the 
description  of  each  under  that  family. 

To  understand  the  significance  of  the  accent  marks  used  with  the  names 
of  the  families,  genera,  and  species,  read  the  footnote  on  page  12. 

This  Spring  Flora  does  not  pretend  to  be  complete  for  any  region.  Its 
purpose  is  to  afford  the  student  sufficient  drill  during  the  spring  term  to  make 
him  thereafter  independent  in  the  use  of  the  larger  Floras.  The  habit  of 
looking  up  the  names  of  plants  leads  incidentally  to  a  knowledge  of  many 
interesting  facts  about  plant  structures  and  relationships. 


SYNOPSIS.  OF  THE   MAIN   GROUPS   OF  THE 
VEGETABLE   KINGDOM. 

Subkingdom  I.    Thallophyta.    Thallophytes. 

Body  of  the  plant  not  differentiated  into  root,  stem,  and  leaf,  as  the  terms 
are  used  in  connection  with  the  higher  plants.  No  vascular  bundles  present. 
Under  the  Thallophytes  are  classified  the  following  main  groups :  — 

A.  Myxomycetes,  or   slime-moulds,  which,  in    their   vegetative  state,  are 
masses  of  protoplasm  without  cell  wall,  called  plasmodia.     Multiplication  by 
means  of  asexual   spores.     Destitute   of  chlorophyll,  and   dependent   upon 
organic  materials  produced  by  other  plants.     See  Botany,  page  252. 

B.  Algce.     Unicellular  or  multicellular,  with  true  cell  wall.     Cells  either 
all  alike,  or  some  modified  to  perform  special  functions.     In  most  instances 
possessed  of  chlorophyll,  and  providing  their  own  food.     Reproduction  by 
division,  or  by  asexual  or  sexual  spores.     See  Botany,  page  269. 

C.  Fungi.     Unicellular  or  multicellular,  with  true  cell  wall.     Cells  either 
all  alike,  or  some  modified  slightly  for  special  functions.     Destitute  of  chloro- 
phyll, and  living  as  parasites  or  saprophytes. '   The  cells  are  usually  thread- 
like, and  are  termed  hyphce.     The  masses  of  threads  forming  the  vegetative 
body  of  the  fungus  are  termed  collectively  the  mycelium.     The  hyphse  often 
fuse  where  they  come  in  contact  and  form  a  tissue,  such  as  is  found  in  the 
toadstools.     Reproduction  by  division,  or  by  asexual  or  sexual  spores.     See 
Botany,  page  277. 

Subkingdom  II.     Bryophyta.    Mosses.    Liverworts. 

Plant  body  multicellular,  and  in  the  higher  forms  differentiated  into  stems 
and  leaves ;  but  there  are  no  true  roots,  absorption  from  the  soil  being  car- 
ried on  by  hairs,  known  as  rhizoids.  Chlorophyll  present.  Vascular  bundles 
imperfect  or  wanting.  In  the  life  history  of  an  individual  both  sexual  and 
asexual  generations  occur,  the  former  being  the  more  conspicuous,  and  bear- 
ing the  sexual  organs,  antheridia  and  archegonia.  Reproduction  by  buds, 
asexual  spores,  and  fertilized  egg  cells.  See  Botany,  page  289. 

5 


Introduction  to  Botany. 


Subkingdom  III.    Pteridophyta.     Vascular  Cryptogams.    Ferns,  Horse- 
tails, Club-mosses. 

Plant  body  differentiated  into  true  roots  and  leaf-bearing  shoots.  True 
vascular  bundles  are  present.  Reproduction  as  in  the  Bryophytes.  The  ger- 
mination of  asexual  spores  results  in  small  prothallia,  which  bear  sexual 
reproductive  organs.  The  asexual  generation  or  sporophyte  is  the  more  con- 
spicuous. See  Botany,  page  292. 


Subkingdom  IV.     Spermatophyta.     Seed-bearing    plants.     Flowering 

plants. 

Plant  body  differentiated  into  true  roots  and  leaf-bearing  shoots.  Special 
shoots,  with  shortened  internodes  and  modified  leaves,  form  flowers  for  the 
purpose  of  reproduction.  After  the  fertilization  of  the  egg  the  embryonic  leaf- 
bearing  plant  (the  embryo  in  the  seed)  is  formed,  but  soon  temporarily  ceases 
to  grow,  and  remains  in  an  inactive  condition  until  the  germination  of  the  seed. 
Sexual  generation,  or  gametophyte,  reduced  to  one  or  a  few  cells  within  the 
pollen  grain  and  ovule.  See  Botany,  page  166. 


KEY   TO    SOME   FAMILIES   OF   SPERMATO- 
PHYTES. 

CLASS  I. 
GYMNOSPERM«32.    Ovules  not  inclosed  in  an  ovary. 

Fruit  usually  a  cone,  or  berrylike  by  coherence  of  scales.  CONIFERS,  page  12. 

CLASS  II. 
ANGIOSPERM/E.     Ovules  inclosed  in  an  ovary. 

SUBCLASS  I.  MONOCOTYLEDONS.  Embryo  with  i  cotyledon.  Stem  having  no 
distinct  zones  of  bark,  wood,  and  pith.  Parts  of  the  flower  usually  in  whorls 
of  3.  Leaves  mostly  parallel-veined. 

'A.  Flowers  on  a  spadix  or  fleshy  axis,  without  calyx  or  corolla,  and  without  chaffy 
scales  or  glumes. 

Marsh  herbs  with  long  linear  or  swordlike  leaves,  and  flowers  in  cylindrical  ter- 
minal spikes.  TYPHACE^E,  page  15. 
Terrestrial  plants;  flowers  on  a  spadix  surrounded  by  a  spathe.       ARACE.-E,  page  18. 

B.  Flowers  not  on  a  spadix ;  provided  with  calyx,  or  both  calyx  and  corolla. 

Perianth  adherent  to  ovary  throughout  its  length,  or  apparently  so,  i.e.  ovary  inferior. 

Stamens  i  or  2,  gynandrous,  flowers  very  irregular.          ORCHIDACE/E,  page  26. 

Stamens  3 ;  anthers  extrorse,  opening  lengthwise.  IRIDACE/E,  page  25. 

Stamens  6.    Flowers  borne  on  a  scape  from  a  bulb.      AMARYLLIDACE^,  page  24. 

Perianth  wholly  free  from  the  ovary. 

Segments  of  the  perianth  all  nearly  alike  in  form  and  color,  but  in  the  genus 
Trillium  having  3  green  sepals  and  3  withering- persistent  petals. 

LILIACE/E,  page  19. 
Perianth  of  3  green  sepals  and  3  deliquescent  petals.          COMMELINACE^E,  page  19. 

C.  Flowers  with  sepals  and  petals  reduced  to  mere  scales  and  bristles,  and  inclosed 

in  scalelike  bracts  or  glumes. 

Glume,  a  single  scalelike  bract;  stems  solid.  CYPERACEVE,  page  18. 

Glumes  of  2  sorts  in  pairs;  stems  usually  hollow.  GRAMINE^:,  page  15. 

SUBCLASS  II.  DICOTYLEDONS.  Embryo  with  a  pair  of  opposite  cotyledons. 
Stems  having  distinct  zones  of  bark,  wood,  and  pith.  (In  herbaceous  plants 
the  wood  zone  is  often  not  hard  nor  well  pronounced.)  Parts  of  the  flower 
mostly  in  whorls  of  4  or  5. 

7 


8  Introduction  to   Botany. 

A.  Corolla  and  sometimes  calyx  wanting. 

•    Flowers  monoecious  or  dioecious;     staminate,  and   sometimes  pistillate   flowers   in 

catkins. 

Leaves  oddly-pinnate.   Fruit,  a  nut  inclosed  in  a  husk.   JUG  LAND  ACE,E,  page  27. 

Leaves  simple.     Fruit,  a  i-celled,  many-seeded   pod.     Seeds  downy-tufted  at 

one  end.  SALICACE^E,  page  29. 

Leaves  simple.     The  2-7-celled  ovary  becoming  a  i-celled,  i-seeded  nut,  often 

associated  with  an  involucre,  as  in  the  oak  and  hazel  nut. 

CUPULIFER/E,  page  30. 
Flowers  not  in  catkins. 

Pistil  more  than  i,  ovary,  or  its  cells,  containing  i  or  only  a  few  ovules. 

Pistils  few  to  many,  and  distinct  or  nearly  so,  calyx  petallike.     Flowers  not  in 
panicles.  RANUNCULACE^,  page  38. 

Pistils  3  'to  6,  calyx  petallike.     Flowers  in  drooping  panicles. 

MENISPERMACEyE,  page  44. 

Pistil  i,  simple  or  compound. 

Herbs  (sometimes  shrubs  or  trees). 

Ovary  i-celled,  inferior;  ovules  2-4.  SANTALACE/E,  page  34. 

Ovary  i-celled,  invested  by  the  tube  of  the  corollalike  calyx. 

NYCTAGINACE^:,  page  36. 

Ovary  i-celled,  free  from  the  commonly  petallike  calyx;  stipules  sheath- 
ing the  stem  at  the  nodes.  POLYGONACE/E,  page  35. 
Ovary  mostly  3-celled.     Plants  usually  exuding  a  milky  secretion  when 
wounded.                                                          EUPHORBIACE^:,  page  72. 

Shrubs  or  trees  (sometimes  herbs). 

Ovules,  a  pair  in  each  cell  of  the  ovary. 

Fruit  a  double  samara.  ACER  in  SAPINDACEJG,  page  74. 

Fruit  a  i-celled,  i-seeded  samara.  OLEACE.E,  page  90. 

Ovules  single  in  each  cell  of  the  i-2-celled  ovary. 

Style  single;  anthers  generally  opening  by  uplifted  valves. 

LAURACE^:,  page  44. 

Style  2-cleft.  URTICACE^E,  page  33. 

Ovules  single  in  each  cell  of  the  2-5-celled  ovary.       RHAMNACE^E,  page  75. 

B.  Corolla  and  calyx  present,  the  former  of  separate  petals,  i.e.  polypetalous. 

(i)  Stamens  more  than  10,  and  more  than  twice  the  sepals  or  lobes  of  the  calyx. 
Pistils  numerous,  separate,  and  concealed  in  a  hollow  receptacle. 

ROSA  in  ROSACES,  page  62. 

Pistils  more  than  i,  separate,  surmounting  a  more  or  less  convex  receptacle. 
Stamens  apparently  inserted  on  the  calyx,  distinct.        ROSACES,  page  56. 
Stamens  inserted  on  the  receptacle. 

Filaments   shorter   than   the   anthers,  stamens  numerous,  sepals   3, 
petals  6.    Trees.  ANONACE^E,  page  38. 

Filaments  longer  than  the  anthers. 

Flowers  dioecious;  woody  climbers  with  small  flowers. 

MENISPERMACE.E,  page  44. 

Flowers  perfect,  petals  deciduous.          RANUNCULACE.*:,  page  38. 
Pistils  several,  cohering  in  a  ring;  stamens  numerous  and  monadelphous. 

MALVACEAE,  page  78. 


Key. 


Pistil  i  as  to  the   ovary,  styles  and   stigmas  sometimes  several. 

Ovary  simple,  i-celled,  2-ovuled.  ROSACES,  page  56. 

Ovary  simple;    numerous  ovules  on   i   parietal   placenta;    leaves  lobed  and 

peltate.  PODOPHYLLUM  in  BERBERIDACE^;,  page  43. 

Ovary  compound,  i -celled. 

Placenta  central.  PORTULACACE.E,  page  36. 

Placentae  parietal,  2  or  more.  PAPAVERACE;E,  page  45. 

Ovary  2-several-celled,  free  from  the  calyx. 

Stamens  5-10  adelphous.  TILIACE^:,  page  78. 

Stamens  monadelphous.  MALVACEAE,  page  78. 

Ovary  2-s-celled;  calyx  borne  at  the  summit,  trees  or  shrubs,  with  stipulate 

leaves.  ROSACES,  page  56. 

Plants  without  stipulate  leaves.  SAXIFRAGACE^E,  page  54. 

(2)  Stamens  of  the  same  number  as  the  petals  and  opposite  them. 

Ovary  i-celled;  style  3-cleft;  sepals  2.  PORTULACACE^G,  page  36. 

Ovary  i-celled;  style  simple.  BERBERIDACE^E,  page  42. 

Ovary  2-6-celled. 

Calyx  lobes  mostly  obsolete ;  plants  climbing  by  coiled  tendrils,  or  sucker- 
like  disks.  VITACE^;,  page  76. 

Calyx  4~5-cleft;  small  shrubs  or  trees.  RHAMNACE/E,  page  75. 

(3)  Stamens  not  more  than  twice  as  many  as  the  petals;  alternate  with  them  when  of 

the  same  number. 

(a)    Ovary  superior;  not  adherent  to  the  calyx. 
Pistils  2  or  more,  and  separate. 

Stamens  coherent  by  their  anthers,  and  united  to  a  fleshy  disk  sur- 
mounting the  two  pistils.  ASCLEPIADACE^:,  page  91. 
Stamens  distinct  on  the  receptacle.     Leaves  punctate. 

RUTACEVE,  page  71. 
Stamens  separate  on  the  receptacle.     Leaves  not  punctate. 

RANUNCULACE>E,  page  38. 
Pistils  2-5,  somewhat  united  at  the  bases  of  the  ovaries;  trees  or  shrubs. 

SAPINDACE^E,  page    74. 

Pistil  i  and  simple,  with  i  parietal  placenta,  or  sometimes  2-celled,  with 
a  row  of  ovules  in  each  cell.  LEGUMINOS.E,  page  65. 

Pistil  i,  compound,  as  shown  by  the  number  of  cells,  placentae,  styles,  or 
stigmas. 
Ovary  i-celled. 

Corolla  irregular;  petals  4,  somewhat  united;    stamens  6,  and 
diadelphous.  FUMARIACE.E,  page  46. 

Corolla  irregular;  petals  and  stamens  5;  placentae  3,  parietal. 

VIOLACE.E,  page  79. 
Corolla  nearly  or  quite  regular. 

Ovule  i ;  styles  or  stigmas  1-3.     Shrubs  or  trees. 

ANACARDIACE,E,  page  73. 

Ovules  more  than  i  on  a  central  or  basal  placenta;  herbs 
with  tumid  nodes.  CARYOPHYLLACE.E,  page  37. 

Ovary  2  or  more  celled. 

Flowers  irregular;  ovary  3-celled.  SAPINDACE^E,  page  74. 

Flowers  nearly  or  quite  regular. 

Stamens  tetradynamous  (sometimes  fewer  than  6)  ;  petals  4. 

CRUCIFER^E,  page  47. 


io  Introduction  to  Botany. 


Stamens   io   (rarely  only  5),  somewhat   monadelphous  at 

base,  leaves  3-foliate,  or  more  or  less  lobed  and  divided. 

GERANIACE^,  page  70. 

Stamens  5,  carpels  3,  pod  inflated.       SAPINDACE/E,  page  74. 
(3)   Ovary  inferior,  being  more  or  less  adherent  to  the  calyx. 
Ovary  i-celled,  many-seeded;  2  parietal  placentae. 

SAXIFRAGACE^E,  page  54. 
Ovary  4-celled  (sometimes  2-celled) ;  pollen  cobwebby. 

ONAGRACE^E,  page  81. 

Ovary  2-5-celled ;  petals  5;  fruit  a  2-several-celled  pome;  shrubs  or  trees. 

ROSACE^E,  page  56. 

Ovary  2-celled ;  style  i;  ovule  i  in  each  cell;  petals  4;  fruit  a  2-seeded 
drupe.  CORNACE^,  page  86. 

Ovary  2-celled;  styles  2;  i  ovule  in  each  cell;  petals  5. 

UMBELLIFER^E,  page  82. 

C.   Corolla  and  calyx  present,  the  petals  more  or  less  united  (gamopetalous). 

(1)  Stamens  more  numerous  than  the  corolla  lobes. 

Pistil  i. 

Ovary  i-celled,  with  i  parietal  placenta.  LEGUMINOS^E,  page  65. 

Ovary  3~i2-celled. 

Stamens  free  from  the  corolla,  or  nearly  so.  ERICACEAE,  page  86. 

Stamens  borne  on  the  base  of  the  corolla.  EBENACE^E,  page  90. 

Ovary  5-celled;  stamens  monadelphous  at  base.  GERANIACE^,  page  70. 

Pistils  several,  their  ovaries  united  in  a  ring;  the  numerous  stamens  monadelphous. 

MALVACEAE,  page  78. 

(2)  Stamens  as  many  as  the  lobes  of  the  corolla,  and  opposite  them. 

Ovary  i-celled,  several-seeded;  style  i.  PRIMULACE^E,  page  88. 

(3)  Stamens  of  the  same  number  as  the  corolla  lobes  (or  fewer),  and  alternate  with  them, 
(a)  Ovary  inferior,  being  surmounted  by  the  other  parts. 

Stamens  united  by  their  anthers  into  a  ring;    flowers  in  an  involucrate 
head.  COMPOSITVE,  page  116. 

Stamens  separate,  and  free  from  the  corolla,  or  nearly  so. 

CAMPANULACE^:,  page  115. 
Stamens  inserted  separately  on  the  corolla. 

Ovary  3-celled.     Stamens  1-4.  VALERIANACE^E,  page  114. 

Ovary  2-5-celled. 

Leaves  opposite,  with  stipules,  or  in  whorls. 

RUBIACE^E,  page  no. 
Leaves  opposite,  without  true  stipules. 

CAPRIFOLIACE^E,  page  112. 

(3)    Ovary  superior,  or  free  from  the  other  parts. 
Corolla  irregular. 

Ovary  4-lobed,  with  i  central  style ;   corolla  labiate. 

LABIAT/E,  page  99. 

Ovary  4-celled,  but  not  lobed,  with  terminal  style;  corolla  somewhat 

2-lipped.  VERBENACE/E,  page  98. 

Ovary    i-celled,   with    free  central    placenta.      Calyx    and    corolla 

2-lipped.     Aquatic  herbs.  LENTIIULARIACE^:,  page  105. 

Ovary  i-celled,  with  2  or  4  parietal  placenta;;  corolla  more  or  less 

2-lipped.  OROBANCHACE^:,  page  106. 


Key. 


ii 


Ovary  and  pod  2-celled  by  the  meeting  of  2  parietal  placentae.     Calyx 
and  corolla  more  or  less  2-lipped.     Trees  or  woody  climbers. 

BIGNONIACE.<E,  page  107. 

Ovary  and  pod  2-celled;    placentae   axillary;    seeds  mostly  few  on 

hooked  projections.  ACANTHACE^:,  page  108. 

Ovary  2-celled;  placentae  axillary,  ovules  mostly  numerous,  not  on 

hooked  projections.  SCROPHULARIACE^E,  page  103. 

Corolla  regular. 

Ovaries  2,  united  only  at  the  top  to  a  fleshy  disk ;  stamens  monadel- 
phous;  pollen  in  horny  masses.  ASCLEPIADACE^E,  page  91. 

Ovary  i. 

Deeply  4-lobed ;  chiefly  rough,  hairy  herbs. 

BORAGINACE/E,  page  96. 

Entire,  i-celled,  with  2  parietal  placentae  (sometimes  appearing 
2-celled  by  union  of  placentae);  usually  hairy  herbs  with 
toothed,  lobed,  or  divided  leaves. 

HYDROPHYLLACE^,  page  95. 
2-celled;  stamens  2-4,  ovules  borne  on  hooked  projections. 

ACANTHACE^;,  page  108. 
2-celled;  stamens  4;  flowers  in  spikes;  chiefly  stemless  herbs. 

PLANTAGINACE^E,  page  109. 

a-celled;  stamens  2;  trees  or  shrubs.  OLEACE^E,  page  90. 

3-celled;  style  3-lobed;  corolla  lobes  5;  stamens  5. 

POLEMONIACE^:,  page  94. 

2-4-celled;  1-2  ovules  in  each  cell;   twining  or  slender  trailing 

herbs;  leaves  alternate.  CONVOLVULACE^:,  page  92. 

2-4-celled,  with  i  erect  ovule  in  each  cell;  style  slender,  stigma 

mostly  2-lobed,  stamens  4.  VERBENACE/E,  page  98. 

2-celled  (rarely  3-5-celled) ;  many  ovules  on  axillary  placentae. 

SOLANACE^E,  page  101. 


MANUAL  OF  SOME  SPRING  FLOWERING 
PLANTS  OF  THE  CENTRAL  AND  NORTH- 
ERN STATES. 

SUB-KINGDOM    SPERMATOPHYTA.     Seed-bearing 
Plants. 

Plant  body  differentiated  into  true  roots  and  leaf-bearing  shoots. 
Special  shoots  with  shortened  internodes  and  modified  leaves  form 
flowers  for  the  purpose  of  reproduction.  Pollen  grains  (microspores) 
containing  the  male  gametophyte  are  borne  in  the  anther  sacs  (micro- 
sporangia)  on  modified  leaves,  known  as  the  filament,  and  the  embryo- 
sac  (macrospore)  containing  the  female  gametophyte  is  borne  in  the 
ovule  (macrosporangium),  which  grows  from  a  much  modified  leaf, 
termed  the  carpel  (see  Botany,  page  203).  After  the  fertilization  of 
the  egg  in  the  embryo-sac  by  the  sperm  from  the  pollen  grain  (see 
Botany,  page  166),  an  embryo  plant,  with  minute  stem,  leaf  or  leaves, 
and  root  fundament,  is  formed,  which  soon  temporarily  ceases  to  grow, 
and  remains  in  an  inactive  condition  until  the  germination  of  the  seed. 

CLASS  I.  —  GYMNOSPERM^E. 

Ovules  borne  upon  an  open  scale  or  disk,  and  not  in  a  closed  ovary ; 
fruit  usually  a  cone,  or  berrylike,  by  coherence  of  scales.  Trees  or 
shrubs,  usually  with  needle-shaped  or  scalelike  evergreen  leaves. 

CONIFERS.    PINE  FAMILY. 

Resinous  trees  or  shrubs,  usually  with  narrow,  scalelike  or  needle- 
shaped  evergreen  leaves.  Wood  without  tracheal  tubes  (water  tubes) 
after  the  first  year's  growth,  the  ring  of  growth  consisting  of  compara- 
tively large  cavitied  tracheids  (wood  fibers  with  numerous  circular  thin 

NOTE.  — The  vowel  is  long  in  the  accented  syllable  when  the  accent  mark 
is  inclined  with  its  apex  to  the  left,  and  short  when  the  accent  is  turned  to  the 
right. 


Gymnospermae.  13 

places  or  pits),  produced  in  the  spring,  and  smaller  cavitied  tracheids 
of  the  later  growth.  Flowers  monoecious,  rarely  dioecious,  borne  in 
catkins,  or  solitary,  destitute  of  calyx  or  corolla. 

Leaves  needle-shaped,  in  clusters  of  2-5.  PINUS  I. 

Leaves  deciduous,  soft  and  needle-shaped,  many  in  a  fascicle.  LARIX  II. 

Leaves  small,  closely  appressed;  branchlets  2-edged  and  flat.  THUYA  III. 

Leaves  awl-shaped,  not  closely  appressed.  JUNIPERUS  IV. 

I.  PINUS.    Pine. 

(The  classical  Latin  name.) 

Leaves  of  two  kinds,  the  first  or  primary  leaves  being  in  the  form  of 
bud  scales,  from  the  axils  of  which  the  secondary,  evergreen,  needle- 
shaped  leaves  arise,  on  very  short  stems,  in  clusters  of  2  to  5.  Stami- 
nate  catkins  borne  at  the  base  of  the  shoot  of  the  current  season  ;  each 
stamen  borne  in  the  axil  of  a  minute  scale ;  anthers  2-celled,  dehiscing 
longitudinally.  Pistillate  catkins,  solitary  or  in  clusters,  borne  just 
beneath  the  terminal  bud,  or  laterally  on  the  young  shoot ;  carpellary 
scales  in  the  axils  of  a  persistent  bract,  and  bearing  a  pair  of  inverted 
ovules  at  its  base.  Fruit,  a  cone  maturing  the  second  autumn. 

1.  Pinus   Strobus,  L.    (Latin  name  of  a  tree  bearing  an  odoriferous  gum.) 
WHITE  PINE.     Leaves  in  clusters  of  fives.     Cone  scales  but  little  thickened  at  the 
end  and  not  sharp  pointed.  Cones  from  4  to  6  inches  long,  about  I  inch  thick  before 
the  scales  spread,  often  slightly  curved.     A  large  forest  tree,  becoming  sometimes 
175  feet  tall. 

2.  Pinus  echinata,  Mill.    (L.,  echinatus,  prickly;  from  echinus,  a  hedgehog.) 
YELLOW  PINE,  SPRUCE  PINE.     Leaves  in  clusters  of  two  and  three.    Cone  scales 
thickened  at  the  apex,  with  prominent  transverse  ridge,  and  slender,  straight, 
deciduous  prickle ;  cones  about  2  inches  long  and  less  than  i  inch  thick  before 
the  scales  spread. 

3.  Pinus  rigida,   Mill.    (L.,  rigidus,  rigid,   stiff.)    PITCH   PINE.     Leaves  in 
clusters  of  threes,  rarely  of  fours,  dark  green  and  rigid.    Cone  scales  thickened 
at  the  apex,  with  transverse  ridge  and  recurved  prickle.    Cones  from  i£  to  3  inches 
long,  becoming  nearly  globular  when  the  scales  spread  ;  often  borne  in  clusters. 

4.  Pinus  sylvestris.    (L.,  sylvestris,  belonging  to  the  woods;   from  sylva,  a 
wood.)     Leaves  in  clusters  of  twos;  cone  scales  thickened^  the  apex;  without 
sharp  points;  cones  tapering.     Introduced  from  Europe,  and  much  planted  as  an 
ornamental  tree. 

H.  LARIX.    Larch. 

(The  ancient  name,  probably  Celtic.) 

Slender  trees  with  soft,  needle-shaped,  deciduous  leaves,  borne  many 
in  a  fascicle.  Catkins  in  early  spring,  terminating  short  spurs  on 


14  Introduction  to  Botany. 

branches  of  the  previous  year.  Pistillate  catkins  crimson  or  red  in 
flower.  Cones  maturing  the  first  year;  their  scales  thin,  without 
prickly  tips,  and  persistent. 

1.  Larix  Americana,  Michx.    TAMARACK,  HACKMATACK,  AMERICAN  BLACK 
LARCH.    Leaves  short,  less  than  i  inch  long ;  cones  5  to  4  inch  long ;  scales  few  and 
rounded.     Mainly  in  cool  swamps. 

2.  Larix  Europaea,  Michx.    EUROPEAN  LARCH.    Leaves  and  cones  longer 
than  in  the  preceding  species ;  cones  many-scaled.    Introduced  from  Europe  as 
an  ornamental  tree. 

III.  THUYA. 

(The  ancient  name.) 

Trees  or  shrubs,  with  short,  lance-shaped,  or  awl-shaped,  or  even 
blunt,  leaves,  which  are  borne  opposite  each  other  in  4  appressed 
rows.  Flowers  monoecious,  both  staminate  and  pistillate  catkins  ter- 
minal and  quite  small ;  staminate  catkins  globose  and  pistillate  catkins 
ovoid  or  oblong.  The  scales  of  the  pistillate  cones  opposite,  and  each 
with  2  erect  ovules  (rarely  2-5  ovules).  Cones  spreading  or  recurved ; 
the  6-io  coriaceous  scales  also  spreading  when  mature. 

i.  Thuya  occidentalis,  L.  (L.,  occidentalis,  pertaining  to  the  west ;  from  occi- 
dere,  to  set.)  ARBOR  VlT&,  WHITE  CEDAR.  Conical  trees;  the  2  lateral  rows 
of  leaves  keeled  and  the  2  outer  rows  flat,  giving  the  branchlets  a  2-edged  appear- 
ance. Mature  cones  from  \  to  £  inch  long,  with  obtuse  scales.  Commonly  planted 
as  an  ornamental  tree. 

IV.  JUNIPERUS.     Juniper. 

(Name  Celtic.) 

Trees  or  shrubs,  with  opposite  4-ranked  leaves,  or  leaves  verticillate 
in  threes;  leaves  small  and  lance-  or  awl-shaped.  Flowers  usually 
dioecious,  but  sometimes  monoecious  ;  catkins  very  small,  the  staminate 
oblong  or  ovoid,  and  the  pistillate  globose,  consisting  of  a  few  fleshy 
scales,  each  bearing  a  single  erect  ovule,  or  rarely  two  ovules.  Globose 
cones  berrylike  by  a  coalescence  of  the  scales,  and  containing  1-6 
bony  seeds. 

1.  Juniperus   communis,  L.    (L.,  communis,  common.)     JUNIPER.    Shrub  or 
low  tree.     Leaves  in   whorls  of  3,  linear,  awl-shaped;    aments   axillary,   cones 
berrylike. 

2.  Juniperus  Virginiana,  L.    RED  CEDAR  or  SAVIN.    From  shrubs  to  tall  trees. 
Leaves   mostly  opposite  and   of  two  forms,   awl-shaped,   or  scalelike.    Aments 
terminal.     Heart  wood  red  and  fragrant. 


Monocotyledones.*  15 


CLASS  II.  —  ANGIOSPER1VLE. 

Ovules  inclosed  in  an  ovary  which  is  composed  of  one  or  more 
spore-bearing  leaves  known  as  carpels  (see  Botany,  page  201),  the 
ripened  ovary  and  contents  constituting  the  fruit. 

Subclass  i.    MONOCOTYLEDONES. 

Embryo  in  the  seed  with  but  one  cotyledon,  the  first  leaves  being 
alternate ;  stem  showing  no  distinction  into  wood,  pith,  and  bark,  the 
vascular  bundles  being  promiscuously  distributed  throughout  the  stem. 
Leaves  mostly  parallel-veined  ;  parts  of  the  flower  usually  in  one  or  more 
whorls  of  threes  or  sixes. 

TYPHACE^.    CAT-TAIL  FAMILY. 

Marsh  or  water  plants,  with  creeping  rootstocks  and  flat,  linear 
leaves,  sheathing  at  the  base.  Flowers  monoecious,  in  dense,  terminal 
spikes.  Parts  of  the  perianth  reduced  to  bristles.  Ovary  i  to  2-celled 
with  as  many  styles.  Fruit  nutlike. 

TYPHA.    Cat-tail  Flag. 

(The  old  Greek  name  Typhe.} 

Plants  erect,  growing  6  feet  or  more  in  height.  Leaves  erect  and 
flat,  sheathing  a  jointless  stem.  Rootstock  creeping.  Flowers  in  ter- 
minal, dense,  cylindrical  spikes,  which  are  staminate  above  and  pistillate 
below.  Pistils  stipulate,  i -celled.  Nutlets  minute  and  long-stalked. 

i.  Typha  latifolia,  L.  (L.,  latus,  broad  \folium,  leaf.)  BROAD-LEAVED  CAT- 
TAIL. Stems  from  4  to  8  feet  tall;  leaves  |  to  I  inch  broad.  Terminal  spikes 
pistillate  below  and  staminate  above ;  staminate  and  pistillate  portions  in  close 
proximity,  and  each  about  3  to  6  inches  long ;  pistillate  portion  i  inch  in  diameter. 
In  marshes  and  wet  places. 

GRAMINEJE.    GRASS  FAMILY. 

Nearly  all  annual  or  perennial  herbaceous  grasses;  usually  hollow 
internodes  and  solid  nodes.  Leaves  alternate,  2-ranked,  sheathing  the 
stem  at  the  base,  the  sheath  split  open  longitudinally  on  the  side  oppo- 
site the  leaf  blade.  Flowers  in  spikelets  which  are  panicled  or  spiked. 
Spikelets  composed  of  one  or  more  flowers  which  may  be  perfect. 


i6 


Introduction  to   Botany. 


monoecious,  or  dioecious,  and'  of  several  2-ranked  bracts  or  glumes. 
Stamens  commonly  3,  and  styles  usually  2,  but  varying  from  i  to  3. 
^,  Ovary  i -celled  and  i-ovuled. 

4 


Fruit  a  seedlike  grain.  See 
Fig.  341  for  a  diagrammatic 
representation  of  the  struc- 
ture of  the  flower. 


I.  POA. 


Meadow-Grass. 
Grass. 


Spear 


Diagrams  of  a  typical  grass  flower,  i,  a  spike- 
let  dissected ;  a  a,  empty  glumes ;  b  b,  fertile 
glumes  bearing  flowers  (c  c)  in  their  axils ; 
d,  a  glume  bearing  the  sterile  flower  (e)  in 
its  axil ;  /  the  palet.  2,  a  cross  diagram  of 
the  same  spikelet  lettered  as  above  \gg,  lodi- 
cules.  3,  a  single  flower  ;  /  palet ;  g,  lodi- 
cule.  —  In  part  after  PRANTL. 


(Greek  name  for  grass  or  fodder.) 

Annuals  or  perennials, 
leaves  flat  or  convolute. 
Spikelets  flattened,  ovate,  or 
lance-ovate,  2-6-flowered,  in 
more  or  less  open  panicles. 
Flowers  usually  perfect,  rarely 
dioecious.  The  two  lower 
glumes  empty,  i-3-nerved ; 
the  glumes  next  the  flower 
longer,  and  usually  with  cob- 
webby hairs  at  the  base,  5- 
nerved  ;  palets  (see  Fig.  341 ) 
shorter  than  the  glumes,  and 
2-nerved  or  2-keeled. 


Poa  pratensis,  L.  (L.,  pra- 
tensis,  growing  in  meadows,  from 
pratum,  a  meadow.)  KENTUCKY 
BLUE  GRASS.  Smooth,  slender 
stems  springing  from  runningroot- 

stocks;  sheaths  sometimes  longer  than  the  internodes;   ligules  short  and  blunt; 

spikelets   nearly  sessile,  3~5-flowered;   upper  glumes  hairy  on  the  margins  and 

keel.    Commonly  planted  for  lawns,  meadows,  etc. 


II.  TRIPS ACUM.    Gama  Grass.    Sesame  Grass. 

(Gr.,  tribo,  to  rub,  in  allusion  to  the  polished  spikes.) 

Stems  solid,  stout  and  tall,  from  thick,  creeping  rootstocks.  Leaves  broad  and 
flat.  Monoecious  spikelets  in  jointed  unilateral  spikes ;  staminate  spikelets  in  the 
upper  part  of  the  spike,  and  the  pistillate  below;  staminate  spikelets  in  pairs, 
2-flowered ;  pistillate  spikelets  with  i  perfect  flower. 


Monocotyledones. 


FIG.  342. 

Cyperus  mflexus.  i,  the 
entire  plant;  2,  a  single 
spike;  3,  the  pistil. — 
After  BRITTON  and 
BROWN. 


FIG.  343. 


Eleocharis  dlbida.  i,  the  entire 
plant ;  2,  the  pistil.—  After  BRIT- 
TON  and  BROWN. 


FIG.  344. 

Scirpus  lacustris.  i,  inflores- 
cence; 2,  basal  portion  of  the 
plant;  3,  a  single  spike;  4,  an 
achene;  5,  scale  of  a  spike; 
6,  bifurcate  style.  —  After  BRIT- 
TON  and  BROWN. 


FIG.  345. 

Car  ex  Meadii.  g,  upper  portion  of  a  plant 
showing  a  staminate  spike  above  and  a 
pistillate  spike  below;  ;-,  a  staminate 
flower ;  s,  a  pistillate  flower. 


i8 


Introduction  to   Botany. 


Tripsacum  dactyloides,  L.  (Gr.,  dakfylos,  finger ;  eidos,  resemblance.)  GAMA 
GRASS.  Stems  4  to  8  feet  tall ;  spikes  single  or  several,  branching  from  a  common 
base.  One  of  our  largest  grasses.  Moist  soil. 


CYPERACE^.    SEDGE  FAMILY. 

Grasslike  or  rushlike  herbs  with  fibrous  roots ;  sometimes  perennial 
by  elongated  rootstocks.  Stems  3~4-angled,  rounded  or  flattened, 
usually  solid.  Leaves  alternate  and  3-ranked,  sheathing  at  the  base, 
and  not  split  open  down  one  side  as  in  grasses.  Flowers  perfect  or 
imperfect  in  i -many-flowered  spikelets ;  i  flower  in  the  axil  of  each 
of  the  glumes  or  bracts.  Style  2-3-cleft ;  fruit  an  acheme,  flattened, 
lenticular,  or  3-angled.  Stamens  usually  3.  The  chief  genera  are 
Cyperus,  Ele6charis,  Scopus,  and  Carex.  (See  Figs.  342-345.) 


ARACE^E.    ARUM  FAMILY. 

Herbs  with  long-petioled,  simple,  or  compound  leaves,  rising  from  a 
corm  or  tuberous  rootstock  ;  sap  usually  very  pungent.  Flowers  monoe- 
cious or  dioecious  and  densely  crowded  on  a  spadix  which  is  usually 
surrounded  by  a  spathe  (see  Fig.  346).  Stamens  4-10  with  short  fila- 
ments ;  ovary  i -several-celled,  with  i-several  ovules 
in  each  cell.  Fruit  usually  a  berry.  Sepals  and 
petals  usually  absent. 

ARISAEMA.    Indian  Turnip.    Dragon  Arum. 
(Gr.,  arz's,  a  kind  of  arum,  and  haima,  blood.) 

Leaves  deeply  divided,  rising  on  long  petioles 
from  a  corm,  and  sheathing  the  base  of  the  simple 
scape.    Flowers  covering  the  lower  part  of  an  elon- 
gated spadix;   spathe   convolute  below  and  over- 
Inflorescence  of  Aris-     hanging  above.     (Fig.  346.)     Flowers  monoecious 
aema.  A  the  spathe,     or  dioecious,  destitute  of  calyx  or  corolla.     Ovary 
shovrin11  the^ow      containing  5  or  6  orthotropous  ovules  rising  from  a 
ers  clustered  at  the     basal  placenta.     Fruit  a  globose  red  berry. 

base  of  the  spadix, 

St  i.  Arisaema  triphyllum,  Torr.    (L., //-*)%//#;»,  s-leaved, 

from  Greek  tri,  three;  phyllon,  leaf.)     INDIAN  TURNIP. 

Jack-in-the-pulpit.     Leaves  3-foliate  with  ovate,  entire  segments.     Spathe  green 
with  purple  stripes,  broad  and  overhanging  at  the  summit.     Rich  woods. 

2.  Arisaema  Dracontium,  Schott.     (Gr.,  drakon,  snake,  or  dragon.)     GREEN 


FIG.  346. 


Monocotyledones.  19 

DRAGON.  Leaves  pedately  divided  into  5-17  segments.  Spadix  long  and  taper- 
ing, exceeding  the  greenish  or  whitish,  narrow,  convolute,  and  pointed  spathe. 
Rich  woods  or  low  grounds. 

COMMELINACEJE.    SPIDERWORT  FAMILY. 

Stems  herbaceous  and  jointed ;  leaves  lanceolate,  linear,  or  ovate, 
sheathing  the  stem  at  the  base,  parallel  veined.  Roots  perennial, 
fibrous,  or  thickened.  Flowers  usually  perfect,  consisting  of  3  per- 
sistent green  sepals,  and  3  blue,  purple,  or  rose-colored,  ephemeral 
petals,  6  stamens,  and  a  single  2-3-celled  superior  ovary,  containing 
3-several  ovules,  and  surmounted  by  a  single  undivided  style.  Fruit 
a  2-3-celled  capsule. 

I.  TRADESCANTIA.    Spiderwort. 
(Tradescant,  gardener  to  Charles  I.  of  England.) 

Stems  upright,  nearly  simple,  and  mucilaginous,  bearing  keeled  leaves.  Flowers 
crowded  in  terminal  or  axillary  umbels ;  filaments  bearded. 

1.  Tradescantia  Virginica,  L.     COMMON  SPIDERWORT.    Leaves  linear  or 
linear-lanceolate,  flat  or  channeled,  sometimes  i  foot  or  more  long;  stems  varying 
in  height  from  about  8  inches  to  3  feet;    leaflike  bracts  subtending  the  inflores- 
cence.    Flowers  of  various  shades  of  blue  and  purple,  from  i  to  2  inches  broad. 
Rich  ground. 

2.  Tradescantia  rosea,  Vent.     (L.,  roseus,  rosy;   from  rosa,  a  rose.)     Leaves 
narrowly  linear  and  grasslike ;    stems  erect,  from  6  to  12  inches  tall ;  bracts  below 
the  flowers  short  and  scarious ;  umbels  on  long  terminal  peduncles ;  rose-colored 
corolla  from  \  to  |  inch  broad.     In  dry  and  sandy  woods. 

LILIACE-3E.     LILY  FAMILY. 

Herbs,  perennial  by  means  of  bulbs,  corms,  or  rootstocks ;  rarely 
woody  plants.  Flowers  regular  and  symmetrical ;  perianth  consisting 
of  6  distinct  or  nearly  distinct  segments,  which  (excepting  in  Trillium) 
are  colored  nearly  alike ;  stamens  6,  borne  on  or  at  the  base  of  the 
perianth,  i  before  each  of  its  segments.  Ovary  superior,  3-celled. 
Fruit  a  loculicidal  capsule  or  a  berry. 

Woody  climbers.  SMILAX  I. 

Not  woody  climbers. 

Flowers  umbellate  on  naked  scapes,  — 

Having  the  odor  of  onions.  ALLIUM  II. 

Not  having  the  odor  of  onions.  NOTHOSCORDUM  III. 

Flowers  in  racemes  or  spikes  on  naked  scapes,  — 

Divisions  of  the  perianth  separate  nearly  or  quite  to  the  base.  CAMASSIA  IV. 

Divisions  of  the  perianth  united  into  a  tube  below.  HvACINTHUS  V. 


2O  Introduction  to   Botany. 


Flowers  borne  on  stems  which  are  leafy,  at  least  near  or  at  the  base,  — 

Stems  leafy  only  at  the  base ;   flower  single  and  erect.  TULIPA  VI. 
Stems  leafy  only  at  the  base;  flower  single  and  nodding.                        ERYTHRONIUM  VII. 

Stem  with  leaves  close  to  the  flower.  TRILLIUM  VIII. 
Stem  simple  and  leafy  throughout,  — 

From  a  scaly  bulb.  LILIUM  IX. 

From  a  rootstock;  flowers  in  terminal  racemes.  SMILACINA  X. 

From  a  rootstock;  flowers  axillary.  POLYGONATUM  XI. 


I.  SMILAX.    Greenbrier. 

(An  ancient  Greek  name.) 

Climbing  by  tendrils  from  the  bases  of  the  petioles.  Leaves  simple, 
parallel  ribbed,  and  netted  veined.  Flowers  dioecious  in  axillary  umbels. 
The  greenish  or  yellowish  perianth  of  6  distinct,  deciduous  segments ; 
anthers  apparently  i -celled  on  linear  filaments ;  ovules  i  or  2  in  each 
of  the  3  cells  of  the  ovary.  Fruit,  a  small  berry. 

1.  Smilax  rotundifolia,   L.     (L.,  rotundas,  round;   folium,  leaf.)     COMMON 
GREENBRIER.    Stems  and  branches  beset  with  sharp  prickles.     Leaves  broadly 
ovate  or  round  ovate,  2  to  3  inches  long,  5-nerved,  abruptly  pointed  at  apex  and 
cordate  at  base.     Peduncles  shorter  or  hardly  longer  than  the  petioles.     Fruit,  a 
blue-black  berry.     Woods  and  thickets. 

2.  Smilax  Pseudo-China,  L.    (Gr.,pseudos,  false.)     Stems  and  branches  without 
prickles,  or  with  very  few.     Leaves  mostly  ovate  or  ovate-oblong,  sometimes  lobed 
at  the  base,  acute  or  cuspidate  at  the  apex,  y-o-nerved.     Peduncles  2-4  times  the 
length  of  the  petiole.     Umbels   i2-40-flowered.     Berries  black.     Dry  or  sandy 
thickets. 

II.  ALLIUM.    Onion.    Garlic. 

(Ancient  Latin  name  of  garlic.) 

Leaves  and  scape  rising  from  a  coated  bulb ;  leaves  linear,  lanceo- 
late-oblong, or  lanceolate.  Flowers  white,  pink,  purple,  or  greenish,  in 
rather  dense  terminal  umbels,  which  are  subtended  by  scarious  bracts. 
Plants  with  the  odor  of  onions.  Ovules,  1-2  in  each  cell. 

1.  Allium  mutabile,  Michx.    (L.,mutabilis,  changeable.)    WILD  ONION.  Coats 
of  the  bulb  fibrous  reticulated ;  scape  from  i  to  2  feet  tall,  pedicels  nearly  i  inch 
long;  divisions  of  the  perianth  thin.     Moist  soil. 

2.  Allium  Nuttallii,  S.  Wats.    (L.  genitive,  of  Nuttall  the  .botanist.)     Bulb  as 
in  the  above  species ;  scape  from  4  to  8  inches  tall ;  pedicels  from  5  to  5  inch  long ; 
perianth  becoming  rigid  in  the  fruit.     On  prairies. 


Monocotyledones.  21 

III.   NOTHOSCORDUM.% 

(Gr.,  nothos,  false;  skordion,  garlic.) 

Similar  to  Allium,  but  without  the  smell  of  onions.  Flowers  greenish 
yellow  in  rather  loose  umbels.  Ovules,  several  in  each  cell  of  the 
ovary. 

i.  Nothoscordum  striatum,  Kunth.  (L.,  striatus,  furrowed;  from  stria,  a 
furrow.)  Scape  usually  less  than  i  foot  high  ;  leaves  narrowly  linear,  thick,  scarcely 
equaling  the  scape;  bracts  of  the  umbel  2,  lanceolate,  persistent;  pedicels  filiform, 
becoming  i  to  2  inches  long.  Flowers  about  \  inch  long,  with  oblong-lanceolate, 
thin  segments.  Open  woods  and  prairies. 


IV.   CAMASSIA. 

(From  native  Indian  name,  quamash  or  cantass.} 

Linear  leaves  and  naked  scape  from  a  coated  bulb.  Flowers  on 
jointed  pedicels  in  bracted  racemes.  Divisions  of  the  perianth  parted 
almost  or  quite  to  the  base,  blue  or  purple.  Ovary  oblong  or  obovate, 
with  a  filiform  style.  Several  seeds  in  each  cell. 

i.  Camassia  Fraseri,  Torr.  (L.  genitive,  of  Fraser.)  WILD  HYACINTH. 
Scapes  from  i  to  2  feet  tall.  Bulb  ovoid ;  leaves  narrowly  linear.  Racemes  3  to  8 
inches  long.  Flowers  on  filiform  pedicels ;  parts  of  the  perianth  narrowly  oblong, 
longer  than  the  stamens ;  blue  to  almost  white.  In  rich  and  moist  ground. 


V.  HYACINTHUS.    Hyacinth. 
(Gr.,  hyakinthos.') 

Perianth  united  into  a  tube  below ;  stamens  inserted  at  the  throat, 
which  is  open  and  spreading.  Flowers  in  spicate  racemes,  varying  in 
color  from  white  through  various  shades  of  blue  and  purple. 

Here  belong  the  cultivated  varieties  of  hyacinth. 


VI.   TULIPA.    Tulip. 
(Per.,  dulband,  a  turban.) 

Stem  i-  or  2-leaved  near  the  ground,  bearing  a  large,  erect  flower; 
perianth  bell-shaped,  of  6  separate  segments,  which  are  broad  and 
erect ;  stigmas  3,  sessile  ;  ovary  triangular ;  seeds  many. 

Here  belong  the  various  kinds  of  cultivated  tulips. 


22  Introduction  to  Botany. 

VII.  ERYTHRONIUM.    Dogtooth  Violet.    Easter  Bell. 
(Gr.,  Erythronion,  name  of  the  European  purple  species;  from  erythros,  red.) 

Scape  bearing  a  single  nodding  flower,  2-leaved  near  the  ground. 
Divisions  of  the  perianth  lanceolate,  spreading  or  recurved  above. 
Stamens  6,  hypogynous,  anthers  not  versatile.  Style  elongated,  thick- 
ened above,  3-lobed  or  cleft.  Flowering  very  early  in  the  spring ;  bulb 
cormlike. 

1.  Erythronium  albidum,  Nutt.    (L.,  albidus,  whitish.)     WHITE  DOGTOOTH 
VIOLET.     Leaves  elliptical  oblanceolate,  very  little  or  not  at  all  spotted.     Flowers 
white,  bluish,  or  purplish;    parts   of   the    perianth    oblong,  tapering,   recurved. 
Asexual  propagation  by  offshoots  from  the  base  of  the  corm.     In  moist  woods  and 
thickets  or  on  prairies. 

2.  Erythronium  mesachorium,   Knerr.     (Gr.,   mesos,  middle;    chora,  land.) 
MIDLAND  DOGTOOTH  VIOLET.     Leaves  narrowly  oblong,  not  spotted,  from  \ 
to  i  inch  wide.     Perianth  not  recurved  nor  much  spreading.     No  offshoots  from 
the  bulbs.    On  open  prairies. 

VIII.  TRILLIUM.    Wake-robin. 

(L.,  triplum,  triple,  all  parts  being  in  threes.) 

Unbranched  herbs.  Stem  rising  from  a  short  rootstock  and  bearing 
near  the  summit  3  leaves  in  a  whorl,  which  subtend  the  solitary  sessile 
flower.  The  outer  whorl  of  the  perianth  of  3  green  sepals,  inner  whorl 
of  3  white,  pink,  purple,  or  greenish  petals.  Six  hypogynous  stamens 
with  linear  anthers.  Ovary  3-celled,  styles  3  ;  numerous  ovules  in  each 
cell. 

1.  Trillium  cernuum,  L.     (L.,  cernuus,  nodding.)     NODDING  WAKE-ROBIN. 
Leaves  broadly  ovate  or  rhombic,  acuminate  above,  2  to  7  inches  long.    Slender 
stems  from  8  to  20  inches  high.    Peduncle  scarcely  14  inches  long,  recurved;  petals 
recurved.     In  rich  woods. 

2.  Trillium  erectum,  L.    (L.,  erectus,  erect.)    ILL-SCENTED  WAKE-ROBIN. 
Stout  stem  from  8  to  16  inches  high.     Leaves  sessile  or  short-petioled.     Petals 
from  i  to  ij  inches  long,  ovate  or  lanceolate.      Peduncle  i\  to  4  inches  long, 
erect  or  declined.     Corolla  spreading.     In  woods. 

3.  Trillium  grandiflorum,  Salisb.      (L.,  grandis,  large;  flos,  floris,  flower.) 
LARGE-FLOWERED  WAKE-ROBIN.    Similar  to  the  above,  but  petals  obovate  or 
oblanceolate,  from  \\  to  2j  inches   long,  white   or  pink,  exceeding   the   sepals. 
Peduncles  erect  or  inclined.    Rich  woods. 


Monocotyledones.  23 

IX.  LILIUM.    Lily. 
(The  classical  Latin  name.) 

Simple  leafy  stems  rising  from  scaly  bulbs.  Large,  showy  flowers, 
erect  or  drooping.  Perianth  colored  all  alike,  or  nearly  so.  Anthers 
6  and  versatile.  Ovary  3-celled  with  2  rows  of  ovules  in  each  cell. 
Style  long,  club-shaped  above,  stigma  3-lobed. 

i.  Lilium  umbellatum,  Pursh.  (L.,  umbella,  a  little  sunshade.)  WESTERN 
RED  LILY,  i  to  3  erect  flowers  which  are  2  to  3  inches  high.  Leaves  narrowly 
linear,  nearly  all  alternate,  or  the  upper  leaves  verticillate.  Bulb  of  narrow,  jointed, 
fleshy  scales.  Perianth  red,  yellow,  or  orange.  In  dry  soil. 

X.  SMILACINA.    False  Solomon's  Seal. 

(Diminutive  of  smilax.) 

Simple  stems  from  creeping  or  thickened  rootstocks.  Leaves  alter- 
nate. Flowers  sometimes  fragrant,  in  terminal  racemes.  Perianth 
6-parted,  white.  Stamens  6,  style  short,  stigma  3-lobed.  Ovary 
3-celled,  2  ovules  in  each  cell.  Berry  i-2-seeded  and  globular. 
Flowers  in  terminal  racemes. 

1.  Smilacina  racemosa,  Desf.    (L.,  racemosus,  full  of  clusters.)     WILD  SPIKE- 
NARD.     Stems  from   i  to  3  feet  high,  bearing  numerous   oblong  lanceolate  or 
oval,  sessile  or   short-petioled  leaves.      Flowers   on  short  pedicels  in  terminal 
racemose  panicles ;  flowers  about  $  inch  broad,  stamens  exceeding  the  parts  of  the 
perianth.     Berries  aromatic,  pale  red,  spotted  with  purple.     Rootstock  thick  and 
fleshy.     Moist  thickets. 

2.  Smilacina  stellata,  Desf.    (L.,  stellatus,  set  with  stars ;  from  stella,  star.) 
Stems  scarcely  i  foot  high,  bearing  7-12  oblong-lanceolate   leaves.      Flowers  in 
simple,  few-flowered  racemes ;  perianth  segments  longer  than  the  stamens.    Berries 
black  or  green  striped  with  black.     In  moist  soil. 

XI.  POLYGONATUM.    Solomon's  Seal. 
(The  ancient  name,  from  Gr., polys,  many;  gony,  knee.) 

Stems  simple,  usually  somewhat  curved,  nearly  erect,  springing  from 
a  jointed  rootstock.  Leaves  sessile  and  partly  clasping.  Flowers  soli- 
tary, or  from  2  to  10  on  drooping  axillary  peduncles  ;  perianth  oblong- 
cylindrical,  or  somewhat  expanded  near  the  apex,  lobes  6  and  short ; 
stamens  6,  included,  more  or  less  adnate  to  the  perianth.  2-6  ovules  in 
each  of  the  3  cells  of  the  ovary,  style  slender ;  stigma  capitate,  somewhat 
3-lobed. 


24  Introduction  to   Botany. 

1.  Polygonatum  biflorum,  Ell.    (L.,  bis,  twice ;  flos,  floris,  flower.)     SMALLER 
SOLOMON'S  SEAL.    Slender  stems,  from  i  to  3  feet  high,  bearing  lanceolate,  oval, 
or  ovate  leaves  which  are  usually  minutely  pubescent  beneath.     Peduncles  1-4, 
usually  2-flowered.     Perianth  from  3  to  2  inch  long.     Filaments  roughened,  inserted 
near  the  summit  .of  the  perianth.    On  wooded  hillsides,  or  in  woods  and  thickets 
generally. 

2.  Polygonatum    giganteum,    Dietrich.     (L.,  giganteus,  gigantic.)      GREAT 
SOLOMON'S  SEAL.    Stout  stems,  from  2  to  7  feet  high,  bearing  ovate  to  lanceolate 
leaves  which  are  from  2  to  6  inches  long ;  not  pubescent  beneath.     Peduncles  2-8- 
flowered ;  flowers  from  £  to  \  of  an  inch  long.     Filaments  smooth,  inserted  about 
the  middle  of  the  perianth  tube.    Along  banks  of  streams  or  in  moist  woods. 


AMARYLLIDACE-3L.    AMARYLLIS  FAMILY. 

Herbaceous  plants  with  scapes  and  flat  linear  leaves  springing  from 
a  bulb,  corm,  or  rootstock.  Corolla  6-parted,  adherent  to  the  ovary; 
stamens  6,  inserted  at  the  base  of  the  perianth  segments  opposite  the 
lobes.  Ovary  usually  3-celled,  with  numerous,  rarely  a  few,  ovules  in 
each  cell.  Style  filiform,  entire,  or  3-lobed  or  divided. 

I.  HYPOXIS.    Star  Grass. 

(Gr.,  hypoxys,  subacid.) 

Scape  and  linear,  hairy  leaves  rising  from  a  corm  or  solid  bulb. 
Flowers  few  on  a  scape.  The  6  parts  of  the  perianth  greenish  outside, 
yellow  within,  separate  nearly  to  the  ovary,  and  withering  on  the  pod. 
Stamens  6 ;  filaments  short ;  anthers  sagittate  or  entire.  Style  short, 
stigmas  3. 

i.  Hypoxis  erecta,  L.  (L.,  erectus,  erect.)  Few-flowered  scape  from  3  to  8  inches 
high.  Leaves  narrowly  linear,  becoming  longer  than  the  scapes.  Perianth  seg- 
ments spreading,  bright  yellow  within,  hairy  and  greenish  without,  and  from  \  to 
nearly  £  inch  long.  In  meadows  and  open  woods. 

II.  NARCISSUS. 

(The  Latin  name.) 

| 

Scape  and  leaves  from  a  coated  bulb.  Tube  of  the  perianth  some- 
what cylindrical,  the  6  segments  widely  spreading ;  a  cup-shaped,  funnel- 
shaped,  or  saucer-shaped  crown  on  the  throat  of  the  perianth  ;  unequal 
stamens  included  in  the  crown. 

Here  belong  the  various  varieties  and  species  of  Narcissus  cultivated 
in  gardens,  and  the  daffodils,  jonquils,  and  Chinese  sacred  lily. 


Monocotyledones.  25 

III.  GALANTHUS.    Snowdrop. 

(Gr.,  gala,  milk;  anthos,  flower.     From  the  color  of  the  flower.) 

Scape  from  a  coated  bulb,  bearing  usually  a  single  nodding  flower. 
The  3  inner  segments  of  the  perianth  shorter  than  the  outer,  and  less 
spreading,  notched  at  the  apex.  Anthers  erect  and  not  versatile. 

i.  Galanthus  nivalis,  Linn.  (L.,  nivalis,  snowy.)  Leaves  2,  linear  and  pale; 
scape  bearing  a  drooping  white  flower;  inner  perianth  segments  tipped  with  green. 
Flowering  in  e arly  spring. 

IRIDACE^.    IRIS  FAMILY. 

Herbs  with  equitant  2-ranked  leaves  rising  from  corms,  rootstocks, 
or  tubers.  The  regular  or  irregular,  mostly  clustered  flowers  usually 
subtended  by  bracts.  Perianth  coherent  to  the  ovary,  the  segments  in 
an  outer  and  an  inner  whorl  of  3  each.  Stamens  3,  separate  or  mona- 
delphous,  inserted  on  the  perianth  opposite  the  outer  whorl  of  segments. 
Ovary  3-celled  and  3-angled  or  lobed ;  ovules  numerous  in  each  cell ; 
style  3-lobed. 

I.  IRIS.    Flower-de-luce. 

(Ancient  name  of  these  flowers,  from  Gr.,  iris,  rainbow.) 

Erect  or  ascending  equitant  leaves  from  horizontal  rootstocks. 
Flowers  large  and  terminal.  Tube  of  the  perianth  somewhat  prolonged 
above  the  ovary,  6-cleft  above,  the  3  outer  segments  broad  and  spread- 
ing or  reflexed,  the  inner  3  segments  erect  as  a  rule  and  usually  nar- 
rower than  the  outer  segments.  The  3  stamens  inserted  at  the  base  of 
the  outer  perianth  segments  ;  anthers  linear  or  oblong.  Ovary  3-celled ; 
style  petallike,  united  below  with  the  tube  of  the  perianth ;  overarching 
above  and  bearing  a  shelflike  stigma  below  the  apex. 

1.  Iris  Germanica,  L.     COMMON  FLOWER-DE-LUCE.      Flowers  large   and 
scentless.     Outer  divisions  of  the  perianth  bearded,  deep  violet,  pendent,  about  3 
inches  long ;  inner,  obovate  divisions  lighter  colored,  and  nearly  as  large. 

2.  Iris  pumila,  L.    (L.,pumilus,  dwarf.)     DWARF  GARDEN  IRIS.    Outer  divi- 
sions of  the  perianth  bearded ;  flowers  few,  violet  or  purple,  close  to  the  ground  in 
early  spring.    Stem  from  4  to  6  inches  high. 


26  Introduction  to  Botany. 

II.  SISYRINCHIUM.    Blue-eyed  Grass. 

(Gr.,  sisyrinchion,  a  bulbous  plant.) 

Grasslike  plants  with  very  short  rootstock  and  fibrous  roots.  Leaves 
linear;  stems  flattened  and  2-edged.  Flowers  umbellate  from  a  pair 
of  green  bracts.  Tube  of  the  perianth  short  or  none;  segments  of  the 
perianth  obovate  or  oblong  and  spreading.  Ovary  3-celled,  with  several 
ovules  in  each  cell ;  branches  of  the  style  threadlike  and  alternating 
with  the  stamens.  Stamens  monadelphous. 

1.  Sisyrinchium  angustifolium,  Mill.     (L.,  angustus,  narrow;  folium,  leaf.) 
Stem  from  3  to  14  inches  tall,  usually  simple,  erect.     Linear  leaves  shorter  than  the 
stem;  narrowly  linear  or  nearly  setaceous  bracts  subtending  the  umbel  very  un- 
equal.    Flowers  white  or  delicate  blue.    Common  in  meadows. 

2.  Sisyrinchium    dnceps,    Cav.      (L.,    anceps,   two-headed.)     Stems  broadly 
2-winged,  from  6  to  18  inches  tall,  terminating  with  two  unequal  branches  above, 
which  are  subtended  by  a  grasslike  leaf.     Bracts  subtending  the  umbels  about 
equal.     In  meadows. 

ORCHIDACEJE.    ORCHIS  FAMILY. 

Perennial  herbs  with  corms,  tubers,  or  tuberous  roots.  Leaves 
sheathing  and  entire,  alternate,  and  plainly  parallel-nerved.  Solitary, 
racemed  or  spiked  flowers,  often  curiously  irregular.  Perianth  in  2 
whorls,  each  of  3  divisions ;  the  3  outer  divisions  or  sepals  more  or 
less  petallike  ;  one  of  the  inner  whorl  or  petals  differing  from  the  others 
in  size  and  shape,  and  termed  the  lip.  Ovary  inferior,  i -celled,  with 
numerous  ovules  on  3  parietal  placentae,  i  or  2  perfect  stamens  cohe- 
rent with  the  style  or  fleshy  stigma  (see  Fig.  289),  forming  what  is  here 
termed  the  column ;  each  cell  of  the  2-celled  anthers  containing  masses 
of  waxy  or  powdery  pollen,  termed  the  pollinia  when  adherent  in  a 
definite  mass. 

L  CYPRIPEDIUM.    Lady's  Slipper. 

(Gr.,  Kypris,  Venus;  podion,  a  buskin,  a  low-cut  woman's  shoe.) 

Stems  or  scapes  leafy ;  leaves  broad  and  many-nerved.  Roots  a  tuft 
of  fleshy  fibers.  Flowers  few  or  solitary,  large  and  drooping.  Sepals 
spreading,  or  2  united  under  the  lip.  The  2  lateral  petals  spreading 
and  usually  narrower  than  the  sepals ;  the  lip  a  large  inflated  sac. 
Column  declined,  having  2  fertile  stamens  laterally  and  a  petaloid 
sterile  stamen  above.  The  broad  terminal  stigma  obscurely  3-lobed. 


Dicotyledones.  27 

i.  Cypripedium  pubescens,  Willd.  (L.,  pubescens,  becoming  downy.)  LARGER 
YELLOW  LADY'S  SLIPPER.  Leafy  stems  from  i  to  2  feet  high.  Leaves  broadly 
oval  or  elliptical;  both  leaves  and  stems  pubescent.  Sepals  elongate-lanceolate. 
Lip  much  inflated,  from  i  to  2  inches  long,  pale  yellow  with  purple  lines.  In  bogs 
or  woods. 

n.  ORCHIS. 

(The  ancient  Greek  name.) 

Stems  scapelike,  from  i-  to  2-leaved  at  the  base.  Roots  fleshy- 
fibrous.  Flowers  in  short  terminal  spikes.  Sepals  and  petals  similar. 
Anther  i  with  divergent  sacs ;  pollinia  attached  by  means  of  a  caudicle 
to  a  basal  viscid  disk,  which  is  inclosed  in  a  pouch. 

i.  Orchis  spectabilis,  L.  (L.,  spectabilis,  showy.)  SHOWY  ORCHIS.  Stems 
4~5-angled ;  2  obovate  leaves  borne  near  the  base,  3  to  6  inches  long.  Spikes  3-6- 
flowered.  Sepals  and  lateral  petals  connivent  above,  pinkish  purple  in  color ;  lip 
whitish  and  obtusely  spurred.  In  rich  woods. 

Subclass  2.    DICOTYLEDONES. 

Embryo  in  the  seed  with  2  cotyledons,  stem  differentiated  into  bark, 
wood,  and  pith,  the  vascular  bundles  being  laid  down  in  the  form  of  a 
ring,  and  possessed  of  a  cambium  zone.  Leaves  mostly  netted-veined. 
Parts  of  the  flower  usually  in  one  or  more  whorls  of  fours  or  fives. 

JUGLANDACE^.     WALNUT  FAMILY. 

Trees.  Leaves  alternate  and  pinnately  compound.  Flowers  monoe- 
cious ;  the  staminate  in  aments,  and  the  pistillate  occurring  singly  or  a 
few  in  a  cluster.  Staminate  flowers  of  3-many  stamens  and  an  irregu- 
lar calyx;  pistillate  flowers  of  a  single  pistil  and  a  4~5-lobed  calyx 
adherent  to  the  ovary.  Ovary  incompletely  2-4-celled  with  a  single 
ovule.  Fruit  a  drupe  with  a  fibrous  or  woody  husk  inclosing  a  bony 
nut.  Embryo  large,  fleshy  and  oily,  the  crumpled  cotyledons  deeply 
2-lobed. 

I.  JUGLANS.    Walnut. 
(L.,  Jovis  glans,  the  nut  of  Jupiter.) 

Staminate  flowers  in  solitary  aments,  produced  from  buds  on  stems 
of  the  previous  year's  growth  ;  stamens  1 2-40  ;  pistillate  flowers  borne 
singly  or  in  groups  at  the  end  of  the  current  season's  growth,  4  small 
petals  borne  in  the  sinuses  of  the  4-toothed  calyx.  Drupe  large  and 


28  Introduction  to   Botany. 

globose  or  ovoid ;  husk  fibrous  and  indehiscent ;  the  shell  or  endocarp 
rugose  or  sculptured. 

1.  Juglans  cinerea,  L.     (L.,  cinereus,  ash-colored.)     BUTTERNUT  or  WHITE 
WALNUT.    Trees,  usually  of  moderate  size  and  rather  smooth  gray  bark;  young 
shoots,  etc.,  viscid-pubescent.     Oblong  lanceolate  leaflets  11-19,  downy  beneath. 
Drupes  oblong  and  pointed  and  clammy.     Rich  woods. 

2.  Juglans  nigra,  L.     (L.,  niger,  black.)     BLACK  WALNUT.    Becoming  large 
trees  with  rough  bark ;  petioles  and  young  shoots  puberulent,  becoming  glabrous 
when  older.    Ovate-lanceolate  leaflets   13-23.    Fruit  globose,  not  viscid.     Rich 
woods. 


H.  CARYA.    Hickory. 

(From  Gr.,  karya,  the  walnut.) 

Staminate  flowers  of  3-10  stamens  in  clustered  lateral  aments ;  pis- 
tillate flowers  in  clusters  of  2-5  on  a  terminal  peduncle.  Calyx  4- 
toothed,  petals  wanting.  Drupes  subglobose,  oblong,  or  ovoid ;  husk 
separating  into  4  valves  ;  nut  bony,  smooth,  or  angled. 

1.  Carya   alba,    Nutt.      (L.,   albus,   white.)      SHELLBARK    or    SHAGBARK 
HICKORY.     Old  bark  falling  off  in  broad  strips.    Leaflets  5,  or  rarely  7,  the  3 
upper  lance-obovate  and  much  larger  than  the  lower.    Opening  terminal  buds 
very  conspicuous,  the  bracts  enlarging  and  persisting  until  the  flowers  are  fully 
developed.    Staminate  flowers  on  slender  peduncles  at  the  bases  of  shoots  of  the 
current  season.     Nut  somewhat  compressed  and  angled,  and  slightly  mucronate 
at  the  apex.    Shell  rather  thin.    Husk  splitting  into  4  valves.    Seed  sweet.     In 
rich  soil. 

2.  Carya  sulcata,  Nutt.  (L.,  sulcatus,  furrowed.)     BIG  SHELLBARK.     Bark 
separating  in  long  strips.     Leaflets  usually  7-9,  downy  beneath.     Nut  from  \\  to 
2  inches  long,  usually  angular  and  prominently  pointed  at  both  ends.    Seed  sweet. 
Husk  and  shell  thick.     Bottom  lands  and  moist  woods. 

3.  Carya  porcina,  Nutt.     (L.,  porcinus,  pertaining  to  a  hog.)    PIGNUT.     Some- 
times becoming  large   trees;    bark   rough;    foliage  usually  smooth,   sometimes 
pubescent;   leaflets  3-7,  infrequently  9,  oblong-lanceolate  or  obovate-lanceolate, 
acuminate,  3  to  6  inches  long.    Fruit  obovoid  or  obovoid-oblong.    Husk  thin,  incom- 
pletely or  tardily  dehiscent.     Nut  thin-shelled,  angled,  and  pointed.     Seed  bitter. 
Uplands. 

4.  Carya  olivaeformis,  Nutt.     (L.,  oliva,  olive;  forma,  form.)     PECANNUT. 
Becoming  tall  trees  with  rough  bark.    Shoots  pubescent  while  young,  but  becom- 
ing glabrous  with  age.    Leaflets  11-15,  short-petioled,  oblong-lanceolate,  and  some- 
what falcate  toward  the  apex.     Staminate  aments  fascicled  near  the  apex  of  the 
previous  year's  growth.    Fruit  from  T.\  to  z\  inches  long,  oblong-cylindrical ;  husk 
thin;  nut  thin-shelled  and  smooth;  seed  sweet.     In  moist  soil  and  along  streams. 


Dicotyledones.  29 


SALICACE^.    WILLOW  FAMILY. 

Shrubs  or  trees  with  light  wood  and  alternate  stipulate  leaves. 
Flowers  dioecious,  both  staminate  and  pistillate  in  aments,  which  expand 
before  or  with  the  leaves.  Stamens  i-many  on  the  concave  receptacle. 
Pistillate  flowers  of  a  single,  i-celled  ovary  with  numerous  ovules  on  2-4 
parietal  or  basal  placentae.  Seeds  tufted  with  silken  hairs. 


I.  POPULUS.    Poplar. 

(The  classical  Latin  name.) 

Trees  with  rounded  or  angular  twigs  and  resinous  buds.  Leaves 
usually  long-petioled,  from  narrow  to  broad.  Staminate  aments  dense 
and  pendulous  ;  pistillate  aments  less  dense,  often  racemelike.  Staminate 
flowers  of  4-60  stamens  ;  stigmas  2-4,  often  large.  Scales  of  the  aments 
more  or  less  fringed.  Flowers  appearing  before  the  leaves. 

1.  Populus  alba,  L.    (L.,  albus,  white.)    WHITE  POPLAR.  Young  branches  and 
under  surface  of  leaves  white  tomentose.     Bark  smooth  and  light  gray.     Leaves 
truncate-ovate  to  nearly  orbicular,  with  acute  apices,  irregularly  dentate  or  3-5- 
lobed.     Producing  suckers  from  adventitious  buds  on  the  roots.     Often  planted  for 
shade. 

2.  Populus  monilifera,  Ait.     (L.,  monile,  necklace  ;  ferre,  to  bear.)     COTTON- 
WOOD.    A  large  tree  with  grayish  green  bark  which  becomes  roughened  with  age. 
Leaves  smooth  and  shining,  broadly  deltoid-ovate,  acuminate  at  the  apex  and 
crenulate   on   the   margins;    petioles   flattened   and   about  as  long  as  the  blade. 
Stamens  as  many  as  60;   pistillate  flowers  in  long,  pendulous   aments.    Along 
streams  and  in  moist  soil. 

H.  SALIX.    Willow. 

(The  classical  Latin  name.) 

Shrubs  or  trees.  Leaves  entire,  usually  long  and  pointed,  with  short 
petioles ;  branches  very  slender.  Staminate  flowers  of  i-io,  usually 
2  stamens.  Bracts  of  the  aments  entire ;  flowers  with  small  glands. 
Buds  with  a  single  scale  and  lining  membrane. 

i.  Salix  nigra,  Marsh.  (L.,  niger,  black.)  BLACK  WILLOW.  Stamens  3-7 
with  pubescent  filaments ;  capsule  ovoid  and  about  twice  as  long  as  the  pedicel ; 
leaves  short-petioled,  narrowly  lanceolate,  and  green  on  both  sides.  Stipules  nearly 
cordate,  conspicuous.  Along  banks  of  lakes  and  streams. 


30  Introduction  to  Botany. 

2.  Salix  amygdaloides,  Anders.      (Gr.,  amygdale,  an  almond;   eidos,  form.) 
PEACH-LEAVED  WILLOW.    Stamens  more  than  2 ;  with  pubescent  filaments ;  cap- 
sule acutely  and  narrowly  ovoid,  about  as  long  as  the  pedicel;   leaves  slender- 
petioled,  broadly  lanceolate  with  long  acuminate  apex ;  dark  green  above  and  paler 
and  somewhat  glaucous  beneath.    Stipules  fugacious.    Along  streams,  etc. 

3.  Salix  lucida,  Muhl.    (L.,  lucidus,  bright.)     SHINING  or  GLOSSY  WILLOW. 
Stamens  5,  the  filaments  pubescent  near  their  bases.     Capsules  longer  than  the 
pedicels  and  narrowly  ovoid.     Leaves  ovate  to  lanceolate,  long  acuminate,  serrulate 
on  the  border,  green  and  shining  on  both  surfaces.     Stipules  glandular  and  nearly 
cordate  to  oblong. 

4.  Salix  longifolia,  Muhl.   (L.,  longus,  long ;  folium,  leaf.)   SANDBAR  or  RIVER- 
BANK  WILLOW.    Stamens  2  with  pubescent  filaments.     Capsules  ovoid  or  conical, 
glabrous  or  silken.     Leaves   linear-lanceolate  or  linear-oblong,  acuminate,  and 
sparingly  denticulate.    Stipules  small  or  none.     Generally  a  much-branched  shrub. 
Occurring  in  thickets  along  lakes  and  water  courses. 

5.  Salix  Missouriensis,  Bebb.    MISSOURI  WILLOW.    Stamens  2  with  glabrous 
filaments.     Glabrous  capsules  narrowly  ovoid,  and  3  or  4  times  longer  than  the 
pedicels.    Leaves  lanceolate  to  oblanceolate,  acuminate,  finely  serrate,  with  minute 
glands  on  the  teeth,  green  above  and  pale  or  glaucous  beneath.    Stipules  about  £  inch 
long.    Becoming  tall  trees  with  thin  gray  bark.    Along  river  banks. 


CUPULIFERJE.    OAK  FAMILY. 

Trees  or  shrubs  with  monoecious  flowers,  the  staminate  flowers  in 
aments  or  clustered ;  the  pistillate  flowers  either  solitary  or  clustered  or 
in  catkins.  Fruit  a  I -celled  and  I -seeded  nut,  with  or  without  an  in- 
volucre. Ovary  2-7-celled  with  1-2  ovules  in  each  cell,  but  becoming 
reduced  in  number  in  the  fruit. 


I.  BETULA.    Birch. 

(The  ancient  Latin  name.) 

Trees  or  shrubs.  Flowers  of  both  kinds  in  aments,  expanding  before 
or  with  the  leaves.  Staminate  flowers  in  clusters  of  threes  in  the  axil 
of  each  bract  of  the  ament,  each  flower  consisting  of  two  2-parted  fila- 
ments bearing  i  anther  sac  on  each  fork.  Pistillate  flowers  from  i  to  3 
in  the  axil  of  each  bract,  without  a  perianth.  Ovary  2-celled  and  styles  2. 
Fruit  becoming  a  small,  compressed,  laterally  winged  nut.  Leaves  thin 
and  dentate  or  serrate. 

i.  Betula  papyrifera,  Marsh.  (Gr.,  papyros,  papyrus  rush ;  L.,  ferre,  to  bear.) 
PAPER  or  CANOE  BIRCH.  Trees  with  chalky-white  bark.  Leaves  ovate  and  finely 
dentate,  smooth  and  green  above,  and  glandular  and  pubescent  on  the  veins  beneath. 


Dicotyledones.  31 

Bark  on  trunk  and  old  branches  pealing  off  in  thin  layers.    Fruiting  aments 
peduncled.    Nut  narrower  than  the  wings.     In  rich  woodland  and  along  streams. 

2.  Betula  occidentalis,  Hook.    (L.,  occidentalis,  western.)     WESTERN  RED 
BIRCH.     Trees  with  smooth  brown  or  greenish  brown  bark.     Leaves  from  ovate  to 
nearly  orbicular,  sharply  serrate ;  smooth  on  both  sides  or  only  slightly  pubescent 
on  the  veins  beneath;    Nut  narrower  than  the  wings.    Fruiting  aments  peduncled. 

3.  Betula  nigra,  L.     (L.,  niger,  black.)     RIVER  or  RED  BIRCH.    Slender  trees 
with  reddish  brown  or  greenish  brown  bark  which  peels  in  thin  layers.     Rhombic 
ovate  leaves  which  are  dark  green  and  smooth  above,  and  pale  and  smooth  or 
somewhat  tomentose  beneath.    Obovate  nut  broader  than  the  wings.     Pistillate 
aments  peduncled.    Along  streams,  etc. 

H.  CARPINUS.    Hornbeam  or  Ironwood. 

(The  ancient  Latin  name.) 

Trees  or  shrubs  with  smooth  gray  bark,  and  leaves  with  lateral  veins 
from  the  midrib  nearly  parallel  and  straight.  Inflorescence  expanding 
before  the  leaves.  Staminate  aments  sessile  at  the  ends  of  short 
branches;  i  staminate  flower  of  3-12  stamens  in  the  axil  of  each  bract 
of  the  ament ;  short  filaments  2-cleft,  each  branch  bearing  an  anther 
sac.  Two  pistillate  flowers  in  the  axil  of  each  bract  of  the  small  termi- 
nal pistillate  aments.  Ovary  2-celled  ;  stigmas  2,  sessile,  or  nearly  so. 
Fruit  a  small,  ovate,  nerved  nut,  subtended  by  a  persistent  foliaceous 
bractlet. 

i.  Carpinus  Caroliniana,  Walt.  AMERICAN  HORNBEAM  or  BLUE  or  WATER 
BEECH.  Small  tree  with  slender  gray  twigs.  Leaves  ovate-oblong,  acuminate, 
very  sharply  doubly  serrate,  somewhat  falcate  or  inequilateral,  green  on  both  sides, 
and  nearly  smooth ;  bractlet  subtending  the  nutlet  3-lobed  and.  halberd-shaped. 
Along  streams  and  in  moist  woods. 

m.  OSTRYA.    Hop  Hornbeam  or  Ironwood. 

(Greek  name  for  hardwood  tree.) 

Slender  trees  with  brownish  bark  and  furrowed  trunks.  Leaves 
ovate  or  oblong-ovate,  somewhat  inequilateral,  slightly  pubescent  above 
.and  beneath,  petioles  very  short.  Staminate  flowers,  of  several  stamens, 
occurring  singly  in  the  axil  of  each  bract ;  filaments  forked,  each  fork 
bearing  an  anther  sac.  Two  pistillate  flowers  in  the  axil  of  each  bract 
of  the  short  pistillate  ament ;  a  tubular  bractlet  surrounding  each  flower 
and  becoming  bladdery  in  fruit  and  completely  inclosing  the  small  nut- 
let. Ovary  incompletely  2-celled,  with  2  ovules ;  stigmas  2,  long  and 
linear.  Border  of  the  adherent  calyx  short  and  bearded. 


Introduction  to   Botany. 


i.  Ostrya  Virginica,  Willd.  AMERICAN  HOP  HORNBEAM.  Leaves  sharply 
doubly  serrate ;  tubular  bractlets  bristly  hairy  at  the  base.  Nutlets  flattened  and 
shining.  In  rich  woods. 

IV.  CO'RYLUS.    Hazelnut  or  Filbert. 

(The  classical  Latin  name.) 

Shrubs  or  small  trees,  with  broad,  thin  leaves  serrulate  or  incised. 
Staminate  flowers  of  about  4  stamens,  solitary,  in  the  axil  of  each  bract 
of  the  staminate  aments,  which  terminate  the  shoots  of  the  previous 
year;  filaments  2-forked,  each  fork  bearing  an  anther  sac.  Pistillate 
flowers  clustered  at  the  end  of  short  branches  of  the  current  season, 
each  flower  consisting  of  a  calyx  adnate  to  an  incompletely  2-celled 
ovary,  which  is  surmounted  by  a  short  style  and  2  slender  stigmas. 
Fruit,  a  large  bony  nut,  inclosed  in  2  foliaceous  or  coriaceous  bractlets, 
which  are  closely  adherent  and  often  grown  together  at  the  lacerated 
margins. 

1.  Corylus  Americana,  Walt.    HAZELNUT.     Shrubs  with  ovate  or  broadly 
oval  leaves,  glabrous  above  and  tomentose  beneath.    Bractlets  compressed  beyond 
the  apex  of  the  nut,  and  laciniate  along  the  margins.     In  thickets. 

2.  Corylus    rostrata,  Ait.    (L.,  rostratus,  beaked.)       BEAKED    HAZELNUT. 
Shrubs  with  nearly  glabrous  ovate  or  narrowly  oval  leaves,  with  margins  incised- 

serrate  and  serrulate.  Bractlets 
prolonged  beyond  the  nut  into  a 
long,  tubular,  laciniate  beak.  In 
thickets. 

V.  QUERCUS.    Oak. 

(The  classical  Latin  name.) 

Trees  or  shrubs.  Flowers 
appearing  before  or  with  the 
leaves.  Staminate  flowers  of 
a  2-8-parted  or  lobed  calyx 
and  3-12  stamens.  Pistillate 
flowers  solitary  or  somewhat 
clustered,  subtended  by  a 
scaly  involucre,  which  be- 
comes a  hard  cup  in  the  fruit. 
Ovary  nearly  3-celled,  with  2 
ovules  in  each  cell,  becoming 
usually  a  i -celled  and  i-seeded 
acorn  or  nut.  (Fig.  347.) 


Diagrams  of  the  flowers  of  an  oak.  x,  stami- 
nate flower;  y,  pistillate  flower;  z,  longitudi- 
nal diagram  of  a  pistillate  flower.  —  After 
STRASBURGER. 


Dicotyledones.  33 

1.  Quercus  rubra,  L.     (L.,  ruber,  red.)     RED  OAK.    Leaves  oval  or  obovate, 
obes  usually  triangular  and  bristle-tipped.    Acorns  about  i  inch  long,  and  about 
2-4  times  as  long  as  the  flat  or  saucer-shaped  cup.     In  rich  or  poor  soils. 

2.  Quercus  alba,  L.    (L.,  albus,  white.)    WHITE  OAK.    Leaves  obovate,  green 
above  and  pale  or  somewhat  glaucus  beneath,   divided  into  3-9  oblong  lobes, 
which  are  often  toothed  at  the  apices,  but  not  bristle-pointed.     Acorns   ovoid- 
oblong,  becoming  sometimes  i  inch  long  and  from  3  to  4  times  as  long  as  the 
shallow  cup.     In  various  soils. 

3.  Quercus  macrocarpa,  Michx.   (Gr.,  makros,  long;  karpos,  fruit.)    BUR  OAK. 
Leaves  obovate  or  oblong-obovate,  variously  lobed,  pinnatifid  or  crenate,  bright 
green  above  and  grayish  tomentulose  beneath.    Acorn  from  \  to  i\  inches  long, 
about  half  immersed  in,  or  scarcely  exceeding,  the  cup,  whose  uppermost  bracts 
are  extended  in  the  form  of  a  fringe.     In  rich  soil. 

4.  Quercus  Prinus,  L.     (Gr.,  prinos,  the  evergreen  oak.)     ROCK  CHESTNUT 
OAK.     Leaves  obovate,  oblong,  or  oblong-lanceolate,  and  coarsely  crenate,  dark 
green   and  smooth  above,  grayish  tomentulose  beneath.     Acorns  I  to  ij  inches 
long,  and  from  2  to  3  times  as  long  as  the  tuberculate  cup.     In  dry  soil  or  on  rocky 
banks. 

URTICACE-ffi.    NETTLE  FAMILY. 

Trees,  shrubs,  or  herbs  with  monoecious,  dioecious,  or  sometimes 
perfect  flowers,  and  leaves  with  stipules.  The  perfect  flowers  with  a 
regular,  inferior  calyx.  Ovary  superior,  i -celled,  rarely  2-celled.  Sta- 
mens as  many  as  the  calyx  lobes,  and  opposite  them,  or  fewer. 


I.  ULMUS.    Elm. 

(The  classical  Latin  name.) 

Trees  with  2-ranked,  simple,  serrate,  straight-veined  leaves,  with  per- 
fect or  polygamous  flowers  in  lateral  clusters,  expanding  before  the 
leaves.  Calyx  4-9-lobed  and  campanulate.  Flowers  in  clusters  on 
•twigs  of  the  preceding  season ;  cells  of  the  ovary  1-2,  each  with  a 
single  ovule ;  the  2  styles  diverging,  and  stigmatic  along  the  inner 
edge  ;  fruit  a  i -seeded  samara,  winged  all  around. 

1.  Ulmus  Americana,  L.    AMERICAN  or  WHITE  ELM.    Leaves  oval  or  obo- 
vate, only  slightly  roughened  above,  2-4  inches  long.    Branches  without  corky 
wings  (as  in  the  case  .of  those  of  the  winged  elm,  Ulmus  alata).     Samara  ovate- 
oval,  nearly  5  inch  long,  ciliate  on  the  margins  of  the  reticulate-veined  wing.    Along 
streams  or  in  rich  and  moist  soil. 

2.  Ulmus  fulva,  Michx.    (L.,/u/vus,  tawny.)    SLIPPERY  or  RED  ELM.    Leaves 
from  ovate  to  obovate,  much  roughened  above,  doubly  serrate,  4  to  8  inches  long. 
Branches  without  corky  wings,  inner  bark  very  mucilaginous.     Samara  from  £  to 
|  of  an  inch  long,  without  ciliate  borders.     In  rich  soil. 


34  Introduction  to  Botany. 

n.  CELTIS.    Hackberry. 

(Pliny's  name  for  an  African  lotus.) 

Trees  or  shrubs,  bearing  polygamous  or  monoecious,  rarely  dioecious, 
flowers  in  the  axils  of  leaves  on  shoots  of  the  current  season.  Stami- 
nate  flowers  in  clusters,  and  the  pistillate  usually  solitary,  but  sometimes 
in  clusters  of  2  or  3.  Sepals  distinct  or  calyx  4-6-parted.  Ovary 
i-celled,  with  a  single  ovule.  Fruit  an  ovoid  or  globose  drupe. 

i.  Celtis  occidentalis,  L.  (L.,  occidentalis,  western.)  HACKBERRY.  Leaves 
ovate  or  ovate-lanceolate,  often  inequilateral,  serrate,  usually  thin.  The  globose 
drupes  purple,  black,  or  orange  when  mature.  In  woods  and  along  river  banks. 

m.  MORUS.    Mulberry. 

(The  classical  Latin  name.) 

Trees  or  shrubs  with  milky  sap.  Flowers  monoecious  or  dioecious, 
the  staminate  and  pistillate  flowers  on  separate  spikes,  the  pistillate 
spikes  becoming  juicy,  aggregate  fruits.  Stamens  4;  perianth  4-parted, 
persisting  in  the  pistillate  flowers  and  becoming  fleshy,  and  inclosing 
the  ovary,  in  the  fruit. 

i.  Morus  rubra,  L.  (L.,  ruber,  red.)  RED  MULBERRY.  Leaves  ovate  to  or- 
bicular, rough  above  and  pubescent  beneath.  Pistillate  spikes  i  to  15  inches 
long ;  staminate  spikes  longer.  Fruit  dark  purple  when  ripe.  In  rich  woods. 

SANTALACE.3S.    SANDALWOOD  FAMILY. 

Herbs  or  shrubs.  Leaves  entire,  opposite  or  alternate,  from  oval  to 
lanceolate.  Flowers  perfect,  monoecious  or  dioecious ;  inflorescence 
various.  Calyx  campanulate,  3-6-lobed,  adnate  to  the  ovary  below. 
Stamens  of  the  same  number  as  the  calyx  lobes  and  opposite  them. 
Ovules  2-4  and  pendulous  from  the  top  of  the  i -celled  ovary.  Fruit  a 
i -seeded  drupe  or  nut. 

I.  COMANDRA.    Bastard  Toadflax. 

(Gr. ,  konte,  hair,  and  andres,  for  stamens,  in  allusion  to  hairs  on  calyx  lobes  attached  to 

the  stamens.) 

Erect  perennial  herbs,  sometimes  growing  parasitically  on  the  roots 
of  other  plants.  Stamens  5,  rarely  4,  inserted  at  the  base  of  the  lobes 
of  the  campanulate  or  urn-shaped  calyx,  and  between  the  lobes  of  a 


Dicotyledones.  35 

fleshy  disk ;  anthers  connected  to  the  middle  of  the  calyx  lobes  by  tufts 
of  hairs.     Globose  fruit  surmounted  by  the  persistent  calyx. 

1.  Comandra  umbellata,  Nutt.      (L.,  umbella,  a  little  sunshade.)     BASTARD 
TOADFLAX.    Stems  slender  and  branched,  from  6  to  18  inches  tall.     Leaves  ses- 
sile, oblong  to  oblong-lanceolate,  somewhat  acute  at  both  ends,  from  £  to  i  inch  and 
more  long.    Flowers  in  corymbose  clusters  near  the  summit  of  the  plant.    Fruit 
globose.    Dry  grounds. 

2.  Comandra   p&lida,  A.  DC.      (L.,  pallidus,  pale.)      PALE   COMANDRA. 
Leaves  linear  or  linear-lanceolate;   flowers  corymbose-clustered.      Fruit  ovoid- 
oblong.     In  dry  soil. 

POLYGON ACE^E.    BUCKWHEAT  FAMILY. 

Shrubs  or  trees,  herbs,  and  twining  vines ;  stems  tumid  at  the  nodes 
and  usually  sheathed  by  the  united  stipules  or  ocreae.  Flowers  small, 
regular,  and  perfect,  monoecious,  dioecious,  or  polygamous  ;  inflorescence 
various.  Stamens  4-12,  inserted  on  the  base  of  the  3-6-lobed  calyx. 
Sepals  sometimes  petaloid,  petals  none.  The  superior  ovary  i -celled 
with  a  single  erect  or  pendulous  ovule.  Fruit  usually  a  3-angled  achene. 

I.  RUMEX.    Dock  or  Sorrel. 

(The  ancient  Latin  name.) 

Annual  or  perennial  herbs  with  grooved  and  usually  branched  stems 
of  various  habits.  Leaves  entire,  or  undulate,  flat  or  crisped ;  ocreae 
cylindrical  and  fugacious.  Inflorescence  of  simple  or  compound  racemes. 
Calyx  6-parted,  the  inner  3  parts  usually  developing  into  wings  in  the 
fruit.  Stamens  6,  style  3-parted.  Flowers  greenish,  small,  crowded  in 
panicled  racemes. 

1.  Rumex  altissimus,  Wood.   (L.,  superlative  of  altus,  high.)    TALL  or  PEACH- 
LEAVED  DOCK.     Perennial.     Stems  simple  or  little  branched,  2  to  4  feet  tall. 
Leaves  ovate-lanceolate  to  lanceolate,  from  2  to  10  inches  long.     Flowers  densely 
whorled    in    open    panicles.    The    3    inner   sepals    forming    the  wings    usually 
i-tubercled.     Pedicels  about  the  length  of  the  wings,  and  jointed  below  the  middle. 
Moist  soil. 

2.  Rumex  crispus,  L.    (L.,  crispus,  curled.)    CURLED  DOCK.    Perennial.    Stem 
from  i  to  3!  feet  tall,  simple  or  branched  above.    Leaves  lanceolate,  long-petioled, 
3  to  12  inches  long,  crisped  and  wavy-margined.     Flowers  in  loose  whorls;  pedi- 
cels in  fruit  i|-2  times  as  long  as  the  wing  sepals.    Wings  with  a  tubercle.     In 
waste  grounds. 

3.  Rumex  hastatulus,  Baldw.    (L.,  hastatus,  armed  with  a  spear.)    HALBERD- 
LEAVED  SORREL.     Stems  simple,  i  to  2  feet  high  from  a  running  rootstock. 
Leaves  halberd-shaped,  i|  to  3  inches  long.     In  pastures  and  waste  places. 


36  Introduction  to  Botany. 


NYCTAGINACE^.    FOUR-O'CLOCK  FAMILY. 

Herbs  outside  the  tropics.  Leaves  simple  and  entire.  Flowers  per- 
fect;  calyx  corollalike  and  inferior.  Ovary  i -celled  and  i-ovuled. 
Calyx  persisting  in  fruit  and  forming  a  nutlike  pericarp.  Stems  swollen 
at  the  joints ;  an  involucre  below  the  flowers. 


I.  OXYBAPHUS. 

(Gr.,  oxybaphon,  a  vinegar  saucer,  from  the  shape  of  the  involucre.) 

Herbs  with  thick  perennial  roots  and  opposite  leaves.  Flowers  in 
clusters  of  3-5  above  a  5-lobed  involucre  which  enlarges  and  becomes 
membranous  in  the  fruit.  Stamens  3-5,  mostly  3.  Style  filiform. 

i.  Oxybaphus  nyctagineus,  Sweet.  (Gr.  nyx,  night;  L.  ending  agin-.} 
HEART-LEAVED  UMBRELLA-WORT.  Stems  usually  slender  and  angled  or 
4-sided,  from  i  to  3  feet  tall.  Leaves  ovate,  acuminate  at  the  apex  and  cordate  to 
truncate  at  the  base;  all  but  the  uppermost  ones  with  petioles.  Perianth  red; 
stamens  and  style  exserted;  involucre  shorter  than  the  flowers.  Fruit  oblong 
and  very  pubescent.  In  dry  soil. 

PORTULACACEJE.    PURSLANE  FAMILY. 

Usually  succulent  herbs.  Sepals  mostly  2,  seldom  5  ;  petals  4  or  5. 
Stamens  usually  of  the  same  number  as  the  petals,  sometimes  more 
numerous.  Ovary  superior,  i -celled,  style  2-8-cleft  or  divided;  ovules 
2  or  many.  Capsules  opening  by  3  valves,  or  circumscissile. 

I.  CLAYTONIA. 

(Named  from  Dr.  John  Clayton,  early  botanist.) 

Perennial  herbs  with  simple  stems  rising  from  a  bulb,  and  bearing  a 
pair  of  opposite  leaves.  Stamens  5,  adhering  to  the  base  of  the  petals. 
Pod  3-valved  and  3-6-seeded.  Flowers  in  a  loose  raceme  in  early 
spring ;  petals  rose  color,  with  veins  of  a  darker  color. 

1.  Claytonia  Virginica,  L.    SPRING  BEAUTY.    Leaves  3  to  7  inches  long, 
linear-lanceolate.     In  moist  open  woods. 

2.  Claytonia  Caroliniana,  Michx.    CAROLINA  SPRING  BEAUTY.    Leaves  i  to  2 
inches  long,  ovate-lanceolate  or  spatulate  oblong. 


Dicotyledones.  37 


CARYOPHYLLACE^:.    PINK  FAMILY. 

Annual  or  perennial  herbaceous  plants  with  opposite,  entire  leaves, 
and  usually  swollen  nodes.  Flowers  perfect  or  rarely  dioecious.  Sepals 
4  or  5,  separate  or  united  below  into  a  tube.  Petals  of  the  same  num- 
ber as  the  sepals,  or  wanting.  Stamens  twice  as  many  as  the  sepals  or 
fewer.  Ovary  i -celled  or  sometimes  3~5-celled,  containing  few  to  many 
ovules  on  a  central  placenta ;  styles  2-5,  rarely  united.  Fruit  a  dehiscent 
capsule,  or  an  achene  or  utricle. 

I.   SILENE.    Catchfly  or  Campion. 
(Gr.,  sz'alon,  saliva,  from  viscid  exudation  of  some  species.) 

Sepals  united  below  into  a  more  or  less  tubular  campanulate  or  in- 
flated tube,  and  5-toothed  or  cleft  above.  Petals  5,  narrow  and  clawed. 
Stamens  i  o.  Styles  usually  3 .  Ovary  i  -celled  or  incompletely  2-4-celled. 
Pod  dehiscing  by  6  or  3  apical  teeth.  Seeds  spiny  or  tubercled. 

i.  Silene  Virginica,  L.  FIRE  PINK.  A  slender,  perennial,  erect  herb,  with 
flowers  in  terminal  cymes,  crimson,  from  i  to  15  inches  broad;  petals  spreading. 
Calyx  campanulate,  nearly  i  inch  long,  enlarging  in  fruit.  Lower  leaves  spatulate 
to  oblanceolate,  upper  leaves  lanceolate,  opposite.  Open  woods. 

H.  CERASTIUM.    Chickweed. 
(Gr.,  keras,  a  horn.) 

Sepals  distinct  or  united  only  at  the  base,  5,  seldom  4.  Petals  of 
the  same  number  as  the  sepals,  rarely  absent,  emarginate  or  bifid  at 
the  summit.  Stamens  10,  seldom  less.  Capsule  cylindrical,  and  dehis- 
cing by  8-10  teeth.  Pubescent  annual  or  perennial  herbs,  bearing 
dichotomous  cymes  of  white  flowers. 

1.  Cerastium  viscosum,   L.    (L.,  viscosus,  full  of  bird  lime.)     MOUSE-EAR 
CHICKWEED.     Viscid-pubescent,  erect,  or  spreading  stems.    Upper  leaves  ovate 
or  obovate,  lower  spatulate.     Petals  shorter  than  the  sepals.    Flowers  glomerate 
with  pedicels  not  longer  than  the  sepals.    Annuals.     In  grassy  places. 

2.  Cerastium  brachypodum,  Robinson.    (Gr.,  brachys,  short;  pous,podas,  foot.) 
SHORT-STALKED  CHICKWEED.    Viscid-pubescent  annuals,  3  to  10  inches  tall. 
Lower  leaves  oblanceolate  or  spatulate,  upper  linear  to  lanceolate.     Petals  longer 
than  the  sepals.     Pedicels  shorter  or  but  little  longer  than  the  calyx.     In  dry  soil. 

3.  Cerastium  arvense,  L.     (L.,  arvum,  a  plowed  field.)     FIELD  CHICKWEED. 
Tufted,  erect,  or  ascending  perennials;   lower  leaves  linear-oblong,  upper  linear 
to  lanceolate.    Petals  obcordate,  longer  than  the  sepals.     Flowers  cymose,  from 
£  to  i  of  an  inch  broad.     Styles  5.     In  dry  or  rocky  places. 


38  Introduction  to  Botany. 


III.  STELLARIA.    Chickweed  or  Starwort. 

(L.,  stella,  star.) 

Herbs,  mostly  tufted  and  diffuse.  Sepals  distinct  or  only  slightly 
united  at  the  base,  4  or  5.  The  4-5  petals  deeply  2-cleft.  Stamens 
8-10,  rarely  fewer.  Pod  ovoid ;  styles  3-5  ;  valves  twice  the  number 
of  the  styles.  Flowers  white,  solitary  or  cymose. 

i.  Stellaria  media,  Smith.  (L.,  medius,  medium.)  COMMON  CHICKWEED. 
Tufted,  branched  annuals,  decumbent  or  ascending,  4  to  16  inches  long;  stems 
with  i  or  2  longitudinal,  pubescent  lines ;  leaves  ovate  to  oval.  Flowers  small,  on 
slender  pedicels,  in  leafy  cymes,  or  solitary  in  the  axils  of  the  leaves.  Petals 
2-parted,  shorter  than  the  calyx;  stamens  2-10.  The  ovoid  capsule  longer  than 
the  calyx.  Common  in  moist  meadows,  woods,  and  waste  places. 

ANONACE^.    CUSTARD-APPLE  FAMILY. 

Shrubs  or  trees,  with  entire  alternate  leaves.  Sepals  3,  and  petals 
about  6  in  2  whorls;  stamens  many  with  adnate,  extrorse  anthers; 
carpels  several,  distinct  or  coherent,  usually  becoming  fleshy  in  fruit. 

i.  ASI'MINA.  Papaw. 

(From  the  Indian  name,  Assimin.) 

Shrubs  or  small  trees.  Flowers  axillary  and  nodding.  The  3  sepals 
ovate  ;  the  3  outer  petals  larger  than  the  3  inner.  Stamens  and  carpels 
3-15.  Fruit  an  oblong,  fleshy  berry.  Seeds  large  and  flat. 

i.  Asimina  triloba,  Dunal.  (Gr.,  tri,  three;  lobos,  lobe.)  NORTH  AMERICAN 
PAPAW.  Small  trees,  with  obovate-lanceolate  leaves.  Petals  veiny  and  of  a  deep 
reddish  purple.  Flowers  appearing  with  the  leaves.  Fruit  large,  fleshy,  sweet,  and 
edible.  In  rich  woods. 

RANUNCULACE-ffi.    CROWFOOT  FAMILY. 

Annual  or  perennial  herbs  or  climbing  shrubs.  Sepals  often  petal- 
like,  3-15;  petals  of  about  the  same  number  and  sometimes  wanting. 
Stamens  numerous ;  carpels  numerous  or  solitary,  i-celled,  and  i- 
many-ovuled.  Fruit  an  achene,  follicle,  or  berry.  Flowers  regular  or 
irregular. 

Leaves  ternately  or  biternately  compound. 
Flowers  regular. 

Pistils  2  or  more.  ISOPYRUM  I. 

Pistil  i.  ACTEA  II. 

Flowers  irregular.  AQUILEGIA  III. 


Dicotyledones.  39 

Leaves  simple,  variously  lobed  or  divided. 

Flowers  irregular.  DELPHINIUM  IV. 
Flowers  regular. 

With  basal  and  involucral  leaves  only. 

Involucre  more  or  less  remote  from  the  flowers.  ANEMONE  V. 

Involucre  close  to  the  flowers  and  resembling  a  calyx.  HEPATICA  VI. 

With  basal  leaves  only.  MYOSURUS  VII. 

With  both  basal  and  stem  leaves;  involucre  none.  RANUNCULUS  VIII. 


I.  ISOPYRUM. 

(From  ancient  Gr.,  isopyron?) 

Slender  herbs,  with  ternately  decompound  leaves  and  white,  solitary, 
or  panicied  flowers.  Five  deciduous,  petallike  sepals ;  petals  wanting 
in  our  species.  Carpels  2-6  or  more,  forming  a  head  of  follicles  in 
fruit. 

i.  Isopyrum  biternatum,  T.  &  G.  (L.,  bis,  twice ;  terni,  three  each.)  FALSE 
RUE  ANEMONE.  Slender,  paniculately  branched  above,  from  fibrous  or  some- 
times tuberiferous  roots.  Lower  leaves  long-petioled,  biternate,  the  leaflets  lobed 
or  divided.  Stamens  many,  the  filaments  thickened  above.  Pistils  commonly  4, 
spreading  in  fruit.  In  moist  woods  or  on  moist,  shady  banks. 

H  ACTJEA.    Baneberry  or  Cohosh. 
(Gr.,  aktea,  name  of  the  elder.) 

Tall,  erect,  perennial  herbs,  with  regular,  small,  racemose  flowers  and 
large,  ternately  compound  leaves.  Sepals  petallike,  3-5  ;  petals  small, 
3-10,  rather  narrow  and  clawed.  Stamens  numerous;  ovary  I  with 
many  ovules  ;  fruit  a  rather  large  berry. 

1.  Actzea  rubra,  Willd.    (L.,  ruber,  red.)    RED  BANEBERRY.    From  i  to  2. 
feet  high.    Leaflets  toothed  or  cleft.    Racemes  ovate,  pedicels  slender,  berries  red. 
In  rich  woods. 

2.  Actsea  alba, Mill.    (L.,albus,  white).    WHITE  BANEBERRY.    Similar  to  the 
preceding  in  habit.    Racemes  oblong.    Fruiting  pedicels  thick.     Berries  white. 
In  rich  woods. 

m.  AQUILEGIA.    Columbine. 

(L.,  aquilla,  eagle,  with  reference  to  the  spurs  of  the  petals.) 

Erect,  perennial  herbs,  with  showy  flowers  and  ternately  or  biternately 
compound  leaves.  Sepals  5,  regular,  of  the  same  color  as  the  petals ; 
petals  5,  extending  backward  into  hollow  spurs,  concave  and  spreading 
in  front.  Stamens  numerous ;  carpels  5  and  many-ovuled. 


40  Introduction  to  Botany. 

i.  Aquilegia  Canadensis,  L.  WILD  COLUMBINE.  Erect  and  branching, 
from  i  to  2  feet  high.  Flowers  about  2  inches  long,  usually  scarlet  and  yellow, 
nodding  so  that  the  straight  spur  points  upward.  In  woods  or  on  shaded,  rocky 
banks. 

IV.  DELPHINIUM.    Larkspur. 

(From  the  Greek  name,  delphinion.} 

Erect,  branching  annuals  or  perennials,  with  palmately  lobed  or 
divided  leaves,  and  irregular,  showy,  racemose,  or  paniculate  flowers. 
Sepals  5,  petallike,  the  upper  one  prolonged  backward  into  a  spur. 
Petals,  4,  irregular,  the  upper  pair  sending  spurs  into  the  spur  of 
the  sepal,  the  lower  petals  small,  sometimes  wanting.  Carpels  1-5, 
forming  many-seeded  pods  in  fruit. 

1.  Delphinium  azureum,  Michx.     (L.,  azureus,  sky-blue.)     Stems  i  to  2  feet 
high,  slender  and  somewhat  pubescent.    Flowers  blue  to  white,  about  i  inch  long, 
with  upward-curving  spur.    Leaves  deeply  3~5-parted,  the  divisions  again  deeply 
cleft  into   linear  segments.     Racemes  short  and  strict;   follicles  erect.     In  open 
grounds. 

2.  Delphinium  tricorne,  Michx.     (L.,  tricornis,  3-horned.)     DWARF  LARK- 
SPUR.   Stout,   6  inches  to  3  feet  high.     Leaves  5~7-parted,  the   divisions  again 
lobed  or  cleft.     Racemes  4  to  7  inches  long,  loosely  or  compactly  several  to  many- 
flowered.     Flowers  i   inch  or  more  long,  spur  slightly  curved.     Follicles  widely 
spreading.    In  open  grounds. 

V.  ANEMONE.    Windflower. 

(The  old  Greek  and  Latin  name,  from  Gr. ,  anemos,  wind.) 

Perennial  herbs,  with  both  radical  and  stem  leaves,  those  of  the  stem 
forming  an  involucre  near  or  remote  from  the  flower ;  the  radical  leaves 
variously  lobed,  divided,  or  dissected.  Sepals  4-20,  petallike ;  petals 
none.  Fruit  an  achene,  pointed  or  tailed. 

1.  Anemone  Caroliniana,  Walt.    CAROLINA  ANEMONE.    Simple  stem  from  a 
tuberous  root ;  becoming  4  to  10  inches  high.     Basal  leaves  usually  3-divided,  the 
divisions  variously  lobed  or  cleft.     Involucre  of  3  wedge-shaped  divisions,  which 
are  again  3-cleft.     Flowers  from  |  to  ii  inches  broad.    Sepals  6-20,  linear  oblong, 
purplish  or  whitish.     In  open  meadows. 

2.  Anemone  Pennsylvania,  L.    PENNSYLVANIA  ANEMONE.    From  i  to  2  feet 
high;  somewhat  hairy,  particularly  on  the  under  side  of  leaves.     Basal  leaves  3-5- 
parted,  and  the  divisions  variously  cleft ;  long-petioled.     The  leaves  of  both  primary 
and  secondary  involucres  sessile.    Peduncle  branched  above  the  primary  involucre, 
the  branches  bearing  2-leaved  involucres  at  the  middle.     Flowers  from  £  to  i  inch 
or  more  broad;  sepals  white.     Achenes  merely  pubescent  or  smooth.     In  low 
grounds  or  in  woods. 


Dicotyledones.  41 

3.  Anemone  quinquefolia,  L.    (L.,  quinque,  five ;  folium,  leaf.)    WINDFLOWER. 
{Anemone  Nemerosa   in  Gray's  "  Manual.")    4  to  9  inches  high  from  horizontal 
rootstocks.     Basal  leaves  long-petioled,  appearing  later  than  the  flowering  stem. 
5-parted,  the  divisions  dentate.     Involucre  leaves  3~5-parted,  on  slender  petioles. 
Solitary  flower  about  i  inch  broad ;    sepals   4-9,  white  or  purplish.      Achenes 
pubescent,  tipped  with  the  hooked  style.     Margins  of  woods. 

4.  Anemone    patens,    L.     (L.,  patens,    exposed.)      Var.    Nuttalliana,   Gray. 
PASQUE  FLOWER.    Perennial  herbs  rising  from  a  thick  rootstock,  from  6  to  16 
inches  high,  silky- villous.     Basal  leaves  much  divided  into  linear  lobes,  on  slender 
petioles.     Involucre  leaves  a  short  distance  below  the  flowers,  erect,  and  fortning 
a  shallow  cup,  divided  into  linear  segments  above.    Light  bluish  purple  sepals 
ovate-oblong.    Achenes  with  long,  persistent,  plumose  styles.     In  dry  prairies. 

VI.  HEPATICA.    Liverleaf. 

(Gr.,  hepatikos,  from  hepar,  liver;  from  supposed  resemblance  of  leaves  to  the  liver.) 

Low  perennial  herbs  with  long-petioled,  3-lobed,  basal  leaves,  per- 
sisting through  the  winter.  Flowers  rather  large,  solitary,  on  slender 
scapes,  white  or  purple.  Sepals  petallike.  Involucre  of  3  sessile  leaves 
close  under  the  flower  and  resembling  a  calyx. 

1.  Hepatica   triloba,  Chaix.     (Gr.,  tri,  three;  lobos,  lobe.)      ROUND-LOBED 
LIVERLEAF.       Lobes  of  the   leaves   and  of  the  involucre  rounded  or  obtuse. 
Flowers  blue,  purple,  or  white  on  villous  scapes.     In  woods. 

2.  Hepatica  acutiloba,  DC.     (L.,  acutus,  sharp ;   Gr.,  lobos,  lobe.)     SHARP- 
LOBED  LIVERLEAF.    Lobes  of  the  leaves  and  of  the  involucre  acute.     In  other 
respects  closely  resembling  the  preceding  species.     In  woods. 

VH.  MYOSURUS.     Mousetail. 

(Gr.,  tnys,  mouse;  oura,  tail.) 

Small  annuals  with  linear  basal  leaves  and  i-flowered  scapes.  Sepals 
usually  5  with  a  basal  spur.  Petals  5,  small,  with  a  slender  claw  which 
is  nectariferous  at  the  summit.  Stamens  5-25.  Pistils  many  on  a 
slender  axis  which  becomes  greatly  elongated  in  fruit. 

i.  Myosurus  minimus,  L.  (\^.,minimus,  least.)  MOUSETAIL.  From  i  to  6 
inches  high ;  scapes  at  length  longer  than  the  leaves.  The  receptacle  becoming 
an  inch  or  more  in  length.  In  moist  soil. 

VIII.  RANUNCULUS.    Crowfoot  or  Buttercup. 

(Pliny's  name  for  these  plants,  meaning  a  little  frog,  since  many  occur  where  frogs  abound.) 

Annual  or  perennial  herbs,  usually  with  both  basal  and  stem  leaves, 
without  involucres  and  with  both  sepals  and  petals,  flowers  usually  yel- 


42  Introduction  to  Botany. 

low,  sometimes  white  or  red.  Sepals  5  and  deciduous ;  petals  of  the 
same  or  greater  number,  with  a  nectariferous  pit  and  a  scale  at  the  base 
of  the  blade.  Flowers  solitary  or  corymed.  Achenes  capitate  or  spicate, 
tipped  with  the  persisting  style,  numerous. 

1.  Ranunculus  abortivus,  L.    (L.,  abortivus,  abortive.)     SMALL-FLOWERED 
CROWFOOT.     From  6  inches  to  2  feet  high.     Basal  leaves  usually  ovate-reniform. 
crenate,  long-petioled.     Stem  leaves  sessile  and  divided  into  oblong  or  cuneate 
lobes.     Flowers   yellow;  petals  shorter  than  or  equaling  the  calyx;   style  short; 
achenes  smooth,  with  a  minute  beak.    In  the  moist  ground  of  woods  and  banks  of 
streams. 

2.  Ranunculus  micranthus,  Nutt.    (Gr.,  mikros,  small ;  anthos,  flower.)    ROCK 
CROWFOOT.    Similar  to  the  above,  but  basal  leaves  ovate  or  orbicular,  usually 
3-lobed ;  plant  hairy ;  roots  tuberous.     In  rich  woods. 

3.  Ranunculus  recurvatus,  Poir.   (L.,  recurvatus,  curved  backward.)   HOOKED 
CROWFOOT.    From  6  inches  to  2  feet  high ;  leaves  broad,  deeply  3-parted  or  lobed, 
the  lobes  variously  toothed,  long-petioled.     Plant  usually  hairy.     Flowers  yellow, 
from  \  to  nearly  \  inch  broad.    Achenes  tipped  with  a  prominent,  recurved,  hooked 
beak.     In  woods. 

4.  Ranunculus  septentrionalis,  Poir.    (L.,  septentrionalis,  northern.)    SWAMP 
or  MARSH  BUTTERCUP.    A  branching  plant  from  i  to  3  feet  high,  smooth  or  only 
slightly  pubescent.     Roots  fibrous.    Leaves  long-petioled,  3-divided,  the  divisions 
stalked  and  cleft  or  lobed  and  cuneate  at  the  base.     Flowers  yellow,  an  inch  or 
more  in  diameter.     Petals  obovate,  and  twice  the  length  of  the  sepals.    Achenes 
with  an  awl-shaped  beak,  flat  and  broadly  margined.     In  low  and  moist  ground. 

5.  Ranunculus  hispidus,  Michx.    (L.,  hispidus,  bristly.)     HISPID  BUTTERCUP. 
Stems  8  inches  to  2  feet  tall,  ascending  or  spreading.     Densely  hairy  while  young, 
but  becoming  less  so  with  age.    Roots  of  thickened  fibers.    Leaves  3~5-divided,  the 
divisions  ovate,  oblong,  or  obovate.    Flowers  from  \  to  15  inches  broad,  yellow. 
Achenes  narrowly  margined  and  tipped  with  an  awl-shaped  beak.     In  dry  woods 
and  thickets. 

6.  Ranunculus  fascicularis,  Muhl.   (L,.,  fasciculus,  a  small  bundle.)    EARLY  or 
TUFTED  BUTTERCUP.    Tufted  plants  from  6  to  12  inches  tall.    Leaves  petioled, 
3~5-divided,  the  divisions  stalked  and  with   oblong  or  linear    lobes.      Flowers 
yellow,  about  i  inch  broad.     Achenes  slightly  margined  with  awl-shaped  beak. 
Somewhat  pubescent.    Root  fibers  thickened.    On  hills  or  in  woods. 


BERBERIDACEJE.    BARBERRY  FAMILY. 

Herbs  or  shrubs.  Both  sepals  and  petals  imbricated  in  the  bud  and 
usually  in  two  whorls  each,  with  3,  rarely  2-4,  segments  in  each  whorl. 
Stamens  of  the  same  number  as  the  petals  and  opposite  them.  Ovary 
superior,  i -celled.  Anthers  opening  by  uplifted  valves,  excepting  in  the 
genus  Podophyllum. 


Dicotyledones.  43 

I.  BERBERIS.    Barberry. 

(From  Berbery 's,  Arabic  name  for  the  fruit.) 

Shrubs  with  yellow  wood  ;  leaves  often  spiny.  Flowers  usually  ter- 
minal, solitary  or  racemed.  Bractlets  subtending  the  6  sepals.  The 
6  petals  obovate,  with  2  glandular-  spots  (nectaries)  above  the  daw. 
The  6  stamens  sensitive  and  closing  around  the  pistil  when  shocked. 
Fruit  a  i -seeded  berry. 

1.  Berberis  vulgaris,  L.   (L.,  vulgaris,  common.)    EUROPEAN  BARBERRY.   A 
smooth  shrub,  from  6  to  8  feet  high.    Twigs  ash-colored,  leaves  simple,  alternate  or 
fascicled,  obovate  or  spatulate,   bristly  serrate.     Inflorescence  a  many-flowered 
drooping  raceme.    Petals  not  notched.    Berries  oblong.     In  thickets. 

2.  Berberis  Canadensis,  Mill.    AMERICAN  BARBERRY.    Shrubs  from  i  to  6 
feet  high,  with  dark  brown  twigs.     Leaves  obovate  or  spatulate,  with  spreading 
teeth.     Racemes  few-flowered.     Petals  emarginate  or  notched  at  the  apex.    Berries 
from  oval  to  nearly  globose. 

IL  CAULOPHYLLUM.    Blue  Cohosh. 
(Gr.,  kaulos,  stem;  phyllon,  leaf,  the  stem  seeming  to  form  a  stalk  for  the  large  sessile  leaf.) 

Herbs  from  thickened  rootstocks.  Stem  simple,  bearing  a  large  ter- 
nately  compound  leaf,  and  terminated  by  a  raceme  or  panicle  of  greenish 
yellow  or  purplish  flowers.  Sepals  6,  subtended  by  3-4  bractlets. 
Petals  6,  thick  and  somewhat  hooded.  Ovary  finally  bursting  and 
withering  away,  leaving  the  2  spherical,  drupelike  seeds  naked  on  their 
seed  stalks. 

i.  Caulophyllum  thalictroides,  Michx.  (Gr.,  thalictron,  meadow  rue;  eidos, 
form.)  BLUE  COHOSH.  From  i  to  3  feet  high.  Leaflets  2-s-lobed ;  divisions  of 
the  leaf  long-petioled.  Flowers  greenish  purple.  In  rich  woods. 

m.  PODOPHYLLUM.    Mandrake  or  May  Apple. 

(Gr.,  pous,  foot;  phyllon,  leaf.) 

Erect,  perennial  herbs  from  horizontal,  poisonous  rootstocks.  Leaves 
large,  peltate,  and  palmately  lobed.  Flowers  solitary ;  white,  sometimes 
pink.  Sepals  6,  petaloid  and  fugacious.  Petals  6-9,  exceeding  the 
sepals.  Stamens  as  many  or  twice  as  many  as  the  petals,  the  linear 
anthers  dehiscing  longitudinally.  Ovary  usually  i,  and  ovules  in  many 
rows  on  the  large  parietal  placenta.  Fruit,  a  fleshy  berry. 

i.  Podophyllum  peltatum,  L.  (L.,peltatus,  armed  with  a  small  shield.)  MAN- 
DRAKE or  MAY  APPLE.  From  i  to  i£  feet  high.  Flowerless  stems  terminated  by 


44  Introduction  to  Botany. 

a  large,  round,  peltate,  7-9-lobed  leaf.  Flowering  stems  usually  bearing  2  large 
lobed  leaves,  with  petioles  fixed  near  one  side.  Nodding  white  flowers,  sometimes 
nearly  2  inches  broad,  springing  from  the  fork  of  the  leaves.  Fruit  edible,  but 
foliage  and  roots  poisonous.  In  rich  woods. 

MENISPERMACEJE.     MOONSEED  FAMILY. 

Herbaceous  or  woody  climbing  plants,  with  alternate  leaves,  and 
small  dioecious  flowers,  usually  in  panicles.  Carpels  usually  3-6, 
sometimes  more,  superior,  i-ovuled.  Sepals  4-12;  petals  6  in  2  rows, 
sometimes  fewer  or  wanting.  Stamens  nearly  of  the  same  number  as 
the  petals.  Fruit  a  i -seeded  drupe. 

I.  CALYCOCARPUM.    Cupseed. 

(Gr.,  kalyx,  cup;  karpos,  fruit.) 

A  high  climber,  with  long-petioled,  palmately  lobed  leaves.  Flowers 
greenish  in  narrow,  drooping  panicles.  Sepals  6,  petallike  ;  petals  none. 
Stamens  about  12  ;  pistils  3,  with  laciniate  stigmas.  Droop  oval,  and 
flattened  or  hollowed  on  one  side. 

i.  Calycocarpum  Lyoni,  Nutt.  (Latin  genitive  of  proper  name.)  CUPSEED. 
Leaves  5  to  8  inches  long,  palmately  5-y-lobed.  Dioecious  flowers  in  long,  loose 
panicles.  Flowers  about  $  inch  broad.  Drupe  about  i  inch  long  and  black  when 
ripe.  In  rich  woods. 

II.  MENISPERMUM.    Moonseed. 
(Gr.,  mene,  moon;  spernta,  seed.) 

A  tall  climber.  Leaves  in  our  species  on  slender  petioles,  broadly 
cordate-ovate,  entire,  or  3-7-angled  or  lobed.  Sepals  4-8  in  2  rows, 
exceeding  the  6-8  petals.  Flowers  dioecious.  Stamens  12-24  in  the 
staminate  flowers ;  pistils  2-4  in  the  pistillate  flowers,  on  a  short, 
common  receptacle.  Ovary  incurved  after  flowering.  Fruit  globular. 

i.  Menispermum  Canadense,  L.  MOONSEED.  Flowers  small  and  white. 
Leaves  4  to  8  inches  wide,  peltate  near  the  base.  Drupe  \  to  \  inch  in  diameter ; 
the  clusters  of  fruit  resembling  small  grapes.  In  woods. 

LAURACEJE.    LAUREL  FAMILY. 

Aromatic  trees  or  shrubs,  with  mostly  alternate,  simple  leaves,  fre- 
quently marked  with  pellucid  dots.  Petals  none ;  sepals  4-6,  colored. 
Stamens  inserted  on  the  calyx  in  several  whorls ;  anthers  opening  by 
2  or  4  uplifted  valves.  Ovary  superior,  i -celled  and  i-ovuled.  Fruit, 
a  i -seeded  drupe  or  berry. 


Dicotyledones.  45 

I.  SASSAFRAS. 

(Sp.,  sasafras,  used  as  a  popular  name  by  early  French  settlers.) 

Trees,  with  aromatic  bark  and  mucilaginous  leaves  and  twigs. 
Leaves  entire  or  i-3-lobed.  Flowers  dioecious,  yellow,  in  umbelled, 
clustered  racemes,  unfolding  with  the  leaves.  Calyx  6-parted  and 
spreading.  Staminate  flowers  of  9  stamens  in  3  rows.  Pistillate 
flowers  of  an  ovoid  ovary  and  6  abortive  stamens.  Fruit,  an  oblong- 
globose,  blue  drupe. 

i.  Sassafras  officinale,  Nees.  (L.,  officina,  a  shop.)  SASSAFRAS  or  AGUE 
TREE.  Becoming  a  large  tree  with  rough  bark.  Leaves  oval  and  entire,  or 
i-3-lobed,  petioles  about  i  inch  long.  Drupe  about  2  inch  long.  In  dry  or  sandy 
soil  or  in  rich  woods. 

PAP  AVERAGES.    POPPY  FAMILY. 

Herbs,  with  milky  or  colored  secretions,  which  exude  when  the 
plants  are  broken  or  deeply  injured.  Leaves  mostly  alternate  and  with- 
out stipules.  Inflorescence  various,  but  peduncles  mostly  i -flowered. 
Sepals  2-3,  falling  as  the  flower  opens.  Petals  4-6  or  more,  deciduous. 
Stamens  few  to  many,  distinct  and  hypogynous.  Ovary  usually  i -celled, 
many-ovuled.  Fruit,  mostly  a  dry,  i -celled  pod. 

I.  ARGEMONE.    Prickly  Poppy. 
(Gr.,  argema,  a  disease  of  the  eye.     Name  applied  to  a  plant  used  as  a  remedy.) 

Annual  or  biennial  herbs,  with  yellow  secretions  and  lobed  and  spiny- 
toothed  leaves.  Flowers  large  and  showy.  Sepals  2-3,  petals  4-6. 
Stamens  many.  Placentae  4-6,  many-ovuled;  stigma  3-6-radiate, 
dilated.  Capsule  oblong,  prickly,  dehiscent  at  the  apex. 

i.  Argemone  alba,  Lestib.  (L.,  albus,  white.)  WHITE  PRICKLY  POPPY. 
Stout  and  often  tall,  with  pinnatifid  or  pinnately  lobed  leaves.  Flowers  white, 
sometimes  3  to  4  inches  in  diameter.  Capsules  i  to  13  inches  long,  dehiscent  at  the 
apex  by  valves.  On  dry,  open  prairies  or  plains. 

H.  SANGUINARIA.    Bloodroot. 

(Latin  name,  from  sanguis,  blood.     Named  from  the  red  color  of  its  secretion.) 

Low  perennials  from  horizontal  rootstocks ;  secretions  or  latex  red. 
Flower  and  leaf  appearing  together  in  early  spring.  Leaf  rounded  and 
palmate-lobed.  Flower  white,  solitary  on  a  naked  scape.  Sepals  2 


46  Introduction  to  Botany. 

early  deciduous;  petals  8-12,  in  2-3  whorls.  Stamens  many.  Pla- 
centae 2.  Capsule  oblong,  turgid,  i -celled  and  2-valved,  dehiscing  to 
the  base. 

i.  Sanguinaria  Canadensis,  L.  BLOODROOT.  Petioles  6  to  14  inches  long. 
Flowers  I  to  ij  inch  broad.  Flowers  at  first  overtopping  the  leaves,  but  finally 
exceeded  by  them.  In  open  woods. 

III.  STYLOPHORUM.    Celandine  Poppy. 

(Gr.,  stylos,  style;  phero,  to  bear.) 

Low  perennial  herbs  from  stout  rootstocks,  with  both  basal  and  stem 
leaves.  Latex  yellow.  Leaves  pinnatifid.  Flowers  yellow,  clustered 
or  solitary.  Sepals  2,  hairy ;  petals  4 ;  stamens  many.  Placentae  2-4. 
Capsule  oblong  or  ovoid,  hirsute,  dehiscent  to  the  base. 

i.  Stylophorum  diphyllum,  Nutt.  (Gr.,  di,  two ;  phyllon,  leaf.)  YELLOW  or 
CELANDINE  POPPY.  Leaves  pinnatifid,  the  5-7  lobes  sinuate.  Upper  stem  leaves 
opposite.  Plant  becoming  12  to  18  inches  high,  and  the  basal  leaves  4  to  10  inches 
long.  Flowers  terminal,  2-4,  about  i  inch  broad,  deep  yellow.  In  damp  woods. 


FUMARIACEJE.    FUMITORY  FAMILY. 

Delicate,  smooth,  and  succulent  herbs,  with  compound,  dissected 
leaves.  Flowers  irregular.  Sepals  2  and  inconspicuous,  soon  falling 
off;  petals  4,  somewhat  united;  stamens  6,  diadelphous.  Ovary 
i -celled  and  i -seeded,  or  several  seeds  on  2  parietal  placentae. 

I.  DICENTRA.    Dutchman's  Breeches. 
(Gr.,  dis,  twice;  kentron,  a  spur.) 

Corolla  cordate  or  2-spurred  at  the  base ;  the  inner  2  petals  coherent 
above,  and  crested  or  winged  on  the  back.  The  6  stamens,  in  2  sets, 
placed  opposite  the  outer  petals,  the  filaments  somewhat  diadelphous. 
Placentae  2  ;  style  slender ;  and  stigma  2-4-lobed.  Low  perennials,  with 
ternately  compound  and  dissected  leaves.  Flowers  racemose  and  nod- 
ding ;  pedicels  bracted. 

i.  Dicentra  cucullaria,  DC.  (L.  cucullus,  a  hood  or  cap.)  DUTCHMAN'S 
BREECHES.  Delicate,  smooth  herbs  with  ternately  compound,  finely  dissected 
leaves.  Racemes  simple,  4-io-flowered ;  flowers  white  or  whitish,  nodding.  Spurs 
divergent  and  inner  petals  minutely  crested.  In  rich  woods. 


Dicotyledones.  47 

II.  CORYDALIS. 

(Ancient  Greek  name  for  the  crested  lark.) 

Only  the  upper  outer  petal  spurred  at  the  base.  Pod  with  few  to 
many  crested  seeds.  The  interior  petals  narrow  and  keeled  at  the  back. 
Stamens  6  in  2  sets,  opposite  the  outer  petals.  Placentae  2 ;  style 
persistent.  Capsule  linear  or  oblong,  2-valved.  Flowers  in  racemes. 

1.  Corydalis  flavula,  DC.     (L.,  flavus,  golden  yellow.)     PALE  CORYDALIS. 
Flowers  k  to  J  inch  long;   spur  short;  pods  drooping  or  spreading.     Pedicels 
slender  in  the  axils  of  conspicuous  bracts;  flowers  pale  yellow.     Stems  slender, 
diffuse  or  ascending.      Lower   leaves  petioled,  the   upper  nearly  sessile,  finely 
dissected.    In  woods  or  on  rocky  banks. 

2.  Corydalis  micrantha,  Gray.     (Gr.,  micros,  small ;  anthos,  flower.)     SMALL- 
FLOWERED  CORYDALIS.    Similar  to  the  above,  but  with  pods  ascending  and 
short-petioled. 

3.  Corydalis    aurea,  Willd.     (L.,  aureus,   golden.)      GOLDEN    CORYDALIS. 
Flowers  from  \  to  f  inch  long,  spur  conspicuous,  about  half  as  long  as  the  corolla. 
Corolla  golden  yellow.    Pods  spreading  or  pendulous,  becoming  swollen  at  inter- 
vals.   Var.  occidentalis ,  Englm.,  has  the  spur  nearly  as  long  as  the  body  of  the 
corolla.    On  rocky  banks. 

CRUCIFER^.     MUSTARD  FAMILY. 

Mostly  herbs  with  acrid  juice.  Leaves  alternate,  and  flowers  in 
racemes  or  corymbs.  Flowers  cruciform.  Sepals  4 ;  petals  4,  spreading 
in  the  form  of  a  cross.  Stamens  6  (sometimes  fewer)  and  tetradyna- 
mous,  2  being  usually  shorter  than  the  other  4.  Pistil  superior,  consist- 
ing of  2  carpels  united  to  form  a  compound  pistil  with  a  thin  partition 
connecting  the  2  parietal  placentae.  Fruit  a  silique  or  silicic,  usually 
2-celled,  rarely  i -celled. 

FLOWERS,  WHITE. 

I.   SEEDS  IN  2  ROWS  IN  EACH  CELL. 

Pods  more  or  less  compressed  parallel  with  the  partition. 

(a)  Low-tufted  herbs,  often  with  stellate  pubescence.  DRABA  XII. 

(3)  Leaves  lanceolate  or  linear;  pods  at  length  orbicular.  ALVSSUM  XIV. 

(c)  Pods  linear;  seeds  often  wing-margined.  ARABIS  XIII. 
Pods  more  or  less  compressed  at  right  angles  to  the  partition. 

(a)  Pods  short,  obcordate-triangular.  CAPSELLA  X. 
Pods  terete  or  turgid. 

(a")  Pods  elongated,  often  angled ;  valves  i-3-nerved.  SISVMBRIUM  II. 

(3)  Pods  globular  to  oblong-linear;  valves  nerveless.  NASTURTIUM  IV. 

II.      SEEDS   IN    I    ROW,   OR   SINGLE  IN   EACH   CELL. 

Pods  more  or  less  compressed  parallel  with  the  partition. 

(a)  Pods  becoming  orbicular;  leaves  oblong  or  linear;  leafy  throughout. 

ALYSSUM  XIV. 


48  Introduction  to  Botany. 

(£)  Pods  linear,  flattened;  valves  mostly  nerveless;  leafy  throughout. 

CARDAMINE  V. 

(c)  Stems  leafless  below,  from  horizontal,  tuberous  rootstocks.  DENTARIA  VI. 

(d)  Pods  broadly  linear,  nerveless;  stems  low  and  scapelike. 

LEAVENWORTHIA  VIII. 
(*•)  Pods  linear;  valves  mostly  i-nerved;  seeds  usually  winged  or  margined. 

ARABIS  XIII. 
¥ ods  more  or  less  compressed  at  right  angles  to  the  partition. 

(a)   Pod  short,  flat,  rounded,  2-seeded.  LEPIDIUM  I. 

Pods  terete  or  turgid. 

(6)  Pods  elongated,  often  angled;  valves  i-3-nerved.  SISYMBRIUM  II. 

FLOWERS,  YELLOW. 

I.   SEEDS  IN  2  ROWS  IN  EACH  CELL. 

Pods  more  or  less  compressed  parallel  with  the  partition.  * 

(a)  Leaves  pinnatifid;  valves  thin,  finely  veined  and  nerveless.  SELENIA  VII. 

(b)  Low-tufted  herbs,  often  with  stellate  pubescence.  DRABA  XII. 

(c)  Pods  obovoid  or  pear-shaped;  valves  i-nerved.  CAMELINA  XI. 
Pods  terete  or  turgid. 

(a)  Pods  elongated,  often  angled;  valves  i-3-nerved.  SISYMBRIUM  II. 

(<5)  Pods  globular  to  oblong-linear;   valves  nerveless.  NASTURTIUM  IV. 

(c)  Pods  globular-inflated;  leaves  simple  with  stellate  hairs.  LESQUERELLA  IX. 

(d)  Pods  obovoid  or  pear-shaped;  valves  i-nerved.  CAMELINA  XI. 

II.      SEEDS  IN   I   ROW,   OR   SINGLE  IN  EACH  CELL. 

Pods  terete  or  turgid. 

(a)  Pods  elongated,  often  angled;   valves  i-3-nerved;  style  or  beak  short. 

SISYMBRIUM  II. 

(b)  Pods  elongated,  tipped  with  a  stout  beak;  valves  i-s-nerved;  lower  leaves  pin- 

natifid, upper  leaves  dentate  or  entire.  BRASSICA  III. 

FLOWERS,  PURPLE. 

I.  SEEDS  IN  2  ROWS  IN  EACH  CELL. 

Pods  more  or  less  compressed  parallel  with  the  partition. 

(a)  Pods  linear;  seeds  often  wing-margined.  ARABIS  XIII. 

II.  SEEDS  IN  I  ROW  IN  EACH  CELL. 

Pods  more  or  less  compressed  parallel  with  the  partition.  f 

(a)  Pods  linear  and  flattened;  valves  mostly  nerveless;  leafy  throughout. 

CARDAMINE  V. 

(b)  Stems  leafless  below,  from  horizontal  tuberous  rootstocks.  DENTARIA  VI. 
(<:)  Pods  broadly  linear,  nerveless ;  stems  low  and  scapelike. 

LEAVENWORTHIA  VIII. 
(d)  Pods  linear,  mostly  i-nerved;  seeds  often  wing-margined.  ARABIS  XIII. 

I.  LEPIDIUM.    Pepperwort  or  Peppergrass. 
(Gr.,  lepidion,  a  little  scale,  with  reference  to  the  little  pods.) 

Flowers  white  ;  pods  short,  the  boat-shaped  valves  or  carpels  flattened 
contrary  to  the  narrow  partition  ;  pod  2-seeded  and  very  flat.  Stamens 
sometimes  fewer  than  6,  and  petals  sometimes  wanting. 


Dicotyledones.  49 

i.  Lepidium  Virginicum,  L.  WILD  PEPPERGRASS.  Pods  slightly  winged 
above,  orbicular  or  oval,  about  j^inch  broad.  Petals  usually  present.  Basal  leaves 
from  spatulate  to  obovate,  somewhat  pinnatifid.  Stem  leaves  sessile,  lanceolate  or 
linear,  entire  or  dentate.  Pedicels  slender  and  spreading,  from  |  to  £  inch  long  in 
fruit.  Roadsides  and  fields. 

II.  SISYMBRIUM.    fledge  Mustard. 

(Ancient  Greek  name  for  a  plant  of  this  family.) 

Flowers  mostly  white  or  yellow.  Seeds  usually  in  only  i  row  in 
each  cell  of  the  elongated  terete  or  angled  siliques,  sometimes  2-rowed ; 
valves  i-3-nerved.  Mostly  tall  and  erect  annuals  and  perennials. 
Leaves  simple,  entire,  lobed,  or  pinnatifid. 

1.  Sisymbrium  officinale,  Scop.   (L.,  officina,  a  workshop.)    HEDGE  MUSTARD. 
Leaves  runcinate-pinnatifid.       Flowers  yellow;   pods  linear,  about  5  inch  long, 
appressed.     In  waste  places. 

2.  Sisymbrium  canescens,  Nutt.     (L.,  canescens,  becoming  white.)     TANSY 
MUSTARD.     Leaves  2-pinnatifid,  frequently  hoary  or  downy.    Flowers  very  small 
and  yellowish.     Pods  oblong-club-shaped  or  oblong-linear,  shorter  than  the  nearly 
horizontal  pedicels.    Seeds  in  2  rows  in  each  cell.     In  waste  places. 

3.  Sisymbrium    Thaliana,   Gaud.      (Gr.,    thaleia,    blooming.)      MOUSE-EAR 
CRESS.    Leaves  obovate  or  oblong,  entire  or  barely  toothed.      Flowers  white. 
Pods  linear  and  somewhat  4-sided,  longer  than  the  spreading  pedicels.    Slender 
and  branching ;  about  9  inches  tall.    Old  fields  and  waste  places. 

III.  BRASSICA. 

(Latin  name  for  cabbage.) 

Flowers  showy  and  yellow  in  elongated  racemes.  Siliques  sessile, 
elongated,  terete  or  4-sided,  tipped  with  a  more  or  less  elongated  beak ; 
the  convex  valves  i-5-nerved.  Seeds  in  i  row  in  each  cell.  Erect, 
branching,  herbaceous  annuals,  biennials,  or  perennials,  with  basal 
leaves  pinnatifid  and  stem  leaves  dentate  or  nearly  entire. 

1.  Brassica  nigra,  Koch.     (L.,  niger,  black.)     BLACK  MUSTARD.    Pods  from 
\  to  i  inch  long,  slender,  and  appressed.     Flowers  bright  yellow,  from  4  to  nearly 
5  inch  broad.    From  2  to  7  feet  high.    Lower  leaves  slender-petioled,  pinnatifid, 
with  a  large,  terminal  lobe,  the  lobes  dentate ;  the  upper  leaves  much  smaller,  entire, 
and  lanceolate,  or  oblong.     Brassica  juncea,  Cosson.,  has  slender,  erect  pods,  from 
i  to  2  inches  long,  on  slender  pedicels,  and  runcinate-pinnatifid  lower  leaves. 
Brassica  sinapistrum,  Boiss.,  has  spreading  or  ascending  pods  from  5  to  f  inch 
long,  somewhat  constricted  between  the  seeds,  on  stout  pedicels  not  more  than 
\  inch  long  in  fruit.     In  fields  and  waste  places. 

2.  Brassica  campestris,  Linn.      (L.  campestris,  pertaining  to  a  level  field.) 
RUTA-BAGA  or  SWEDISH  TURNIP.    Flowers  creamy  yellow ;  roots  tuberous.     In 
cultivated  grounds. 


50  Introduction  to   Botany. 

IV.  NASTURTIUM.    Water  Cress. 

(L.,  nasus  tortus,  a  wry  nose,  in  allusion  to  the  pungent  qualities  of  the  genu.) 

Flowers  yellow  or  white.  Pods  short  or  elongated,  from  globular  to 
oblong-linear,  terete  or  nearly  so ;  valves  nerveless.  Leaves  mostly 
pinnate  or  pinnatifid.  Seeds  in  most  cases  in  2  rows  in  each  cell. 
Embracing  aquatic  and  marsh  species. 

1.  Nasturtium  officinale,  R.  Br.     (L.,  officina,  workshop.)      TRUE  WATER 
CRESS.     Petals  white,  twice  as  long  as  the  sepals ;  pods  linear,  from  5  to  |  inch 
long;  leaves  with  3-11  odd-pinnate  leaflets.    Aquatic  plants,  rooting  at  the  nodes. 
I  n  brooks  and  ditches. 

2.  Nasturtium  sinuatum,  Nutt.     (L.,  sinuatus,  curved  or  wavy.)     SPREADING 
YELLOW  CRESS.    Flowers  yellow,  about  \  inch  broad.     Pods  linear-oblong,  from 
a  to  |  inch  long,  on  slender  pedicels,  somewhat  elongated.     Low  diffuse  perennials, 
with  lanceolate,  oblanceolate,  or  oblong  leaves,  pinnatifid  into  linear  or  oblong 
lobes,  or  merely  sinuate-dentate,  from  2  to  3  inches  long  and  usually  less  than  an 
inch  in  breadth.     In  moist  ground. 

3.  Nasturtium  pahistre,  DC.    (L.,palus,  a  swamp.)    MARSH  CRESS.    Flowers 
yellow,  from  £  to  |  inch  broad.     Pods  spreading  or  curved,  about  |  inch  long,  on 
pedicels  of  nearly  the  same  length ;  style  quite  short.     Erect,  branching  annuals  or 
biennials.     Lower  leaves  deeply  pinnatifid,  lanceolate,  or  oblanceolate,  petioled ; 
upper  leaves  sessile  or  nearly  so,  dentate  or  lobed.     In  wet  places  or  shallow  water. 


V.  CARDAMINE.    Bitter  Cress. 

(Greek  name  of  a  cress.) 

Flowers  white  or  purple,  in  racemes  or  corymbs.  Pods  linear- 
elongate,  flattened  parallel  with  the  partition,  usually  erect;  valves 
hardly  or  not  at  all  nerved,  dehiscing  elastically  at  maturity.  Seeds  in 

1  row  in  each  cell,  flattened  and  marginless. 

1.  Cardamine  Pennsylvania,  Muhl.    PENNSYLVANIA  BITTER  CRESS.    Erect, 
stout,  or  slender  stems,  8  inches  to  3  feet  tall,  leafy  throughout.     Basal  leaves 

2  to  6  inches  long,  pinnately  divided  into  4-8  pairs  of  mostly  narrow  segments,  the 
terminal  segment  obovate,  oval,  or  nearly  orbicular.     Flowers  white.     Pods  nar- 
rowly linear,  rather  more  or  less  than  i  inch  long.     In  swamps  and  wet  places. 

2.  Cardamine  bulbosa,  B.  S.  P.     (L.,  bulbosus,  full  of  bulbs.)     BULBOUS  CRESS. 
Erect  stems  from  a  tuberous  base,  simple  or  sparingly  branched ;  6  inches  to  i^  feet 
tall.    Basal  leaves  long-petioled,  entire,  oval  to  orbicular,  sometimes  cordate.    Stem 
leaves  mostly  sessile,  oblong  or  lanceolate,  dentate  or  entire.    Flowers  white ;  petals 
much  longer  than  the  calyx.    The  linear-lanceolate  pods  about  i  inch  long.     In 
wet  meadows  and  springs. 


Dicotyledones. 


VI.  DENT  ARIA.    Toothwort  or  Pepperroot. 
(L.,  dens,  a  tooth.) 

Flowers  white,  rose-colored,  or  purple,  in  corymbose  clusters,  petals 
much  exceeding  the  calyx.  Pods  linear  and  flattened,  parallel  with  the 
partition,  dehiscing  from  the  base.  Seeds  in  I  row  in  each  cell.  Peren- 
nial herbs  from  fleshy,  horizontal  roots  tocks.  Stems  leafless  below, 
2-4-leaved  above.  Leaves  3-divided,  or  palmately  laciniate,  petioled. 

1.  Dentaria  laciniata,  Muhl.     (L.,  lacinia,  a  flap.)    CUT-LEAVED  TOOTH- 
WORT  or  PEPPERROOT.     Basal  leaves,  when  present,  similar  to  the  stem  leaves, 
which  are  3-parted,  the  divisions  lanceolate  or  oblong,  lobed  or  cleft.     Leaves 
petioled,  2  to  5  inches  broad  ;  stem  leaves  close  together,  usually  3.     Flowers  rather 
more  than  |  inch  broad,  white  or  pinkish.     In  moist  woods. 

2.  Dentaria  diphylla,  Michx.      (Gr.,  di,  two;  phyllon,  leaf.)     TWO-LEAVED 
TOOTHWORT.    Basal  leaves  long-petioled,  4  to  5  inches  broad,  ternate,  the  divisions 
broadly  ovate,  dentate,  or  lobed  ;  the  two  stem  leaves  similar  to  the  basal  leaves,  and 
opposite  or  nearly  so.     Flowers  white.     In  woods  and  meadows. 

VII.  SELENIA. 

(Gr.,  selene,  the  moon;  from  fancied  resemblance  of  the  pods.) 

Flowers  yellow.  Pods  flattened  parallel  to  the  broad  partition,  oblong, 
and  narrowed  at  both  ends.  Valves  thin,  finely  veined,  and  nerveless. 
Styles  long  and  slender.  Seeds  in  two  rows  in  each  cell.  Low  annuals 
with  pinnatifid  leaves,  and  leafy-bracted  racemes. 

i.  Selenia  aurea,  Nutt.  (L.,  aureus,  golden  yellow.)  Stems  2  to  8  inches  high. 
Basal  leaves  i  to  2  inches  long,  once  or  twice  pinnatifid  ;  stem  leaves  smaller  but 
similar.  Pedicels  about  |  inch  long  in  fruit.  Pod  often  more  than  £  inch  long  and 
i  to  i  inch  broad.  In  open  places. 


LEAVENWORTHIA. 

(Named  from  M.  C.  Leavenworth.) 

Upper  part  of  corolla  white  or  purple,  yellow  toward  the  base.  Pods 
broadly  oblong-linear,  flattened  parallel  to  the  partition,  \  to  i  inch  and 
more  long.  Valves  nerveless,  finely  reticulate-veined.  Seeds  in  i  row 
in  each  cell.  Low  annuals  with  scapelike  stems,  and  lyrate-pinnatifid 
basal  leaves.  Flowers  terminal,  solitary,  or  few. 

i.  Leavenworthia  Michauxii,  Torr.  (L.,  genitive  of  proper  name.)  Stems 
tufted,  3  to  6  inches  high  ;  basal  leaves  i  to  4  inches  long;  stem  leaves  few  or  want- 
ing. Petals  wedge-shaped,  about  twice  the  length  of  the  calyx.  Pods  oblong  or 
linear.  Leavenworthia  torulbsa,  Gray,  is  similar  to  the  above,  but  with  pods  con- 
stricted between  the  seeds.  In  open  dry  places. 


52  Introduction  to   Botany. 

IX.  LESQUERELLA. 

(Named  for  Leo.  Lesquereux.) 

Flowers  yellow.  Pod  globular-inflated,  nerved  from  the  apex  to  the 
middle,  seeds  few  to  several  in  2  rows.  Low  annuals  or  herbaceous 
perennials,  having  simple  leaves  beset  with  stellate  pubescence. 

1.  Lesquerella  globosa,  Watson.     (L.,  globus,  a  sphere.)     Sparingly  branched 
annuals  or  biennials,  6  to  20  inches  high,  beset  with  fine,  stellate  pubescence. 
Basal  leaves  i  to  15  inches  long,  oblong-obovate,  obtuse.    Stem  leaves  smaller, 
linear  or  oblong,  sessile,  entire,  or  margins  slightly  undulate.    Pods  nearly  globular. 
In  open  places. 

2.  Lesquerella  Ludoviciana,  Watson.    Biennials  or  perennials,  6  to  18  inches 
high,  densely  stellate-pubescent  throughout.     Leaves  linear  to  oblanceolate,  blunt 
and  entire,  lower  leaves  2  to  3  inches  long.    Flowers  yellow.     Pedicels  nearly  i  inch 
long,  spreading  or  recurved  in  fruit.     Prairies. 

3.  Lesquerella  gracilis,  Watson.     (L.,  gracilis,  slender.)     Slender,  sparingly 
pubescent  annuals,  much  branched,  i  to  2  feet  tall.    Leaves  linear  to  oblanceolate. 
Pods  globose  and  glabrous.     Prairies. 

X.   CAPSELLA.    Shepherd's  Purse. 

(Latin  diminutive  of  capsat  box.) 

Flowers  white.  Pod  short,  obcordate-triangular,  flattened  contrary 
to  the  narrow  partition.  Seeds  numerous  in  2  rows  in  each  cell. 
Annuals. 

Capsella  Bursa-pastdris,  Moench.  (L.,  meaning  shepherd's  purse.)  Annuals, 
6  to  20  inches  high.  Basal  leaves  clustered  and  more  or  less  pinnatifid  and 
toothed.  Stem  leaves  much  smaller,  few,  often  dentate  and  auriculate.  Flowers 
small  in  an  elongate  raceme.  Pods  on  slender  pedicels,  erect  or  spreading. 
Common  in  waste  places. 

XI.  CAMELINA.    False  Flax. 

(Gr.,  chantai,  dwarf;  linon,  flax.) 

Flowers  yellow  and  small.  Pods  obovoid  or  pear-shaped,  only 
slightly  flattened  parallel  with  the  partition;  valves  i -nerved.  Seeds 
several  in  2  rows  in  each  cell ;  style  slender.  Erect  annuals  with  entire 
or  toothed  and  pinnatifid  leaves. 

i.  Camelina  sativa,  Crantz.  (L.,  sativus,  sown  or  planted.)  GOLD-OF-PLEAS- 
URE  or  FALSE  FLAX,  i  to  2  feet  high.  Leaves  lanceolate,  the  upper  clasping  by 
a  sagittate  base,  mostly  entire.  Pedicels  slender  and  spreading  or  ascending.  In 
fields  and  waste  places. 


Dicotyledones.  53 

XII.  DRABA.    Whitlow  Grass. 

Low  tufted  herbs,  often  with  stellate  pubescence.  Flowers  white  or 
yellow  ;  pods  elliptic,  oblong,  or  linear,  flattened  parellel  with  the  par- 
tition. Seeds  several  in  2  rows  in  each  cell.  Stems  scapose  or  leafy. 

1.  Draba>  verna,  L.      (L.,  verna,  a   native.)      VERNAL  WHITLOW  GRASS. 
Flowers  white  ;  petals  deeply  2-cleft.     I  to  5  inches  high  ;  flowering  stems  leafless. 
Leaves  tufted  at  the  base,  oblong  or  spatulate-oblanceolate,  entire  or  only  dentate, 
beset  with  stiff,  stellate  hairs.    Pods  oblong  or  oval,  smooth,  shorter  than  the 
pedicels.     In  fields  and  sandy  waste  places. 

2.  Draba  Caroliniana,  Walt.    CAROLINA  WHITLOW  GRASS.    Flowers  white  ; 
petals  entire.     Pods  linear,  longer  than  the  ascending  pedicels.     Flowering  stems 
i  to  5  inches  high.    Leaves  obovate  and  entire,  clustered  at  the  base,  or  only  a 
short  distance  up  the  stem,  beset  with  stellate  pubescence. 

3.  Draba  cuneifolia,  Nutt.     (L.,  cuneus,  wedge  ;  folium,  leaf.)     Flowers  white  ; 
petals  emarginate  ;  pods  oblong-linear,  minutely  hairy,  longer  than  the  horizontal 
pedicels.    4  to  8  inches  high,  branching  and  leafy  below;  leaves  obovate,  cuneate, 
or  the  lowest  spatulate,  dentate  toward  the  summit.     In  fields  and  grassy  places. 

4.  Draba  brachycarpa,   Nutt.     (Gr.,  brachys,  short;   karpos,  fruit.)     SHORT- 
FRUITED  WHITLOW  GRASS.     Flowers  yellow  ;  the  oblong  pods  &  to  £  inch  long. 
Basal  leaves  \  to  5  inch  long,  ovate  or  obovate,  stem  leaves  oblong  and  entire. 
Dry  hills  and  fields. 


ARABIS.    RockCress. 

(Named  from  Arabia.) 

Flowers  white  or  purple.  Pods  linear,  elongated,  and  flattened  par- 
allel with  the  partition;  valves  mostly  i-nerved.  Seeds  in  i  or  2  rows 
in  each  cell,  usually  margined  or  winged.  Leaves  seldom  divided. 

1.  Arabis  Ludoviciana,  Meyer.    Stems  ascending  from  5  to  i  foot  high.    Stem 
leaves  pinnatifid,   oblong,   and   narrow.     Flowers    very   small    and   white.     Pods 
linear,  spreading,  nearly  i  inch  long;  seeds  as  broad  as  the  pod,  and  winged.     In 
open  places. 

2.  Arabis  dentata,  T.  &  G.    TOOTHED  ROCK  CRESS.     Petals  greenish  white, 
hardly  exceeding  the  calyx;  pods  narrowly  linear,  sometimes  exceeding  i  inch'  in 
length.     Seeds  oblong,  in  i  row  in  each  cell.     Stems  sparingly  branched,  i  to  2 
feet  high.     Basal  leaves  obovate  and  dentate,  on  margined  petioles;  stem  leaves 
oblong  or  oblanceolate,  dentate,  sessile,  base  auricled  and  clasping. 

XIV.  ALYSSUM. 

(Gr.,  a,  without  or  depriving;  lyssa,  madness.      Greek  name  of  a  plant  supposed  to  have 

remedial  value.) 

Flowers  white  (or  sometimes  yellow).  Pods  orbicular,  flattened  at 
the  margins  parallel  with  the  partition  ;  seeds  only  i  or  2  in  each  cell. 


54  Introduction  to   Botany. 

i.  Alyssum  maritimum,  L.  (L.,  maritimus,  relating  to  the  sea.)  SWEET 
ALYSSUM.  White,  honey-scented  flowers.  Stems  spreading ;  leaves  lanceolate 
or  linear,  entire,  green,  or  slightly  hoary.  Rounded  pods  with  a  single  seed  in 
each  cell.  Cultivated. 

SAXIFRAGACE^.     SAXIFRAGE  FAMILY. 

Herbs  or  shrubs  with  opposite  or  alternate,  exstipulate  leaves. 
Flowers  perfect  or  polygamo-dicecious.  Calyx  mostly  5-lobed  or 
parted,  usually  persistent  and  more  or  less  adnate  to  the  ovary  or  free 
from  it.  Petals  4-5.  Stamens  sometimes  twice  as  many  as  the  petals 
(sometimes  more  numerous),  when  of  the  same  number  alternate  with 
them,  perigynous  or  epigynous.  Carpels  i-several,  mostly  2,  united 
or  free.  Styles  as  many  as  the  carpels  or  cells  of  the  ovary,  or  united 
into  i.  Fruit  a  capsule,  follicle,  or  berry;  seeds  mostly  many. 

I.  SAXIFRAGA.    Saxifrage. 
(L.,  saxum,  a  rock;  fran-gere,  to  break.) 

Perennial  herbs.  Calyx  5-lobed,  free  from  or  adnate  to  the  base 
of  the  ovary.  Petals  5  and  perigynous.  Stamens  10,  inserted  with 
the  petals.  Ovary  2-lobed  and  2-celled.  Capsule  2-beaked.  Seeds 
numerous. 

1.  Saxifraga  Pennsylvanica,  L.    SWAMP  SAXIFRAGE.    Stout,  i  to  3  or  more 
feet  high.     Leaves  4  to  10  inches  long  and  sometimes  3  inches  wide,  varying  from 
oval  to  oblanceolate,  narrowing  at  the  base  into  a  short  petiole,  clustered  at  the 
base.    Stem  scapose,  bearing  flowers  in  large,  oblong,  open  panicles.      Calyx 
reflexed.      Petals   longer   than    the    calyx,  greenish.      Follicles    divergent  when 
mature.    On  wet  banks  or  in  bogs. 

2.  Saxifrage  Virginiensis,  Michx.    EARLY  SAXIFRAGE.    Scapes  4  to  12  inches 
high,  viscid-pubescent.     Leaves  obovate-spatulate,  narrowing  into  a  petiole,  crenate 
or  dentate,  i  to  3  inches  long,  or  longer.     Flowers  clustered  in  cymes,  the  inflores- 
cence becoming  a  loose  panicle.     Flowers  white,  £  to  J  inch  broad.    Calyx  lobes 
erect,   shorter  than  the  petals.     Carpels  nearly  separate  and  becoming  widely 
divergent  in  fruit.    Dry  hillsides  and  rocky  woodlands. 

II.  PHILADELPHIA.    Mock  Orange  or  Syringa. 

(Gr.,#7u70s,  loving;  adelphos,  brother.     No  obvious  reason  for  the  name.) 

Shrubs  with  opposite,  petioled,  exstipulate  leaves.  Flowers  large, 
white  or  cream-colored,  terminal  or  axillary.  Calyx  tube  coherent  with 
the  ovary,  4~5-lobed.  Petals  4-5,  rounded  or  obovate.  Stamens  20-40. 
Ovary  3-5 -celled;  styles  3-5,  distinct  or  united.  Capsule  top-shaped, 


Dicotyledones.  55 

dehiscing  loculicidally.      The   common   name   syringa  is   the   proper 
generic  name  for  the  lilac. 

i.  Philadelphia  coronarius,  L.  (L.,  coron&rius,  pertaining  to  a  wreath.) 
GARDEN  SYRINGA  or  MOCK  ORANGE.  A  shrub  8  to  10  feet  high.  Leaves  2  to  4 
inches  long,  elliptic  or  ovate-elliptic,  pubescent  beneath,  denticulate.  Flowers 
racemose  at  the  ends  of  the  branches,  an  inch  or  more  broad,  creamy  white  and 
fragrant.  Cultivated  ;  escaped  from  gardens  in  some  localities. 

m.  RIBES.    Gooseberry  and  Currant. 
(Ar.,  ribes,  gooseberry.) 

Shrubs  with  alternate  and  often  fascicled,  lobed  leaves.  Calyx  5- 
lobed,  the  tube  coherent  with  the  ovary.  Petals  5  and  small,  inserted 
at  the  throat  of  the  calyx.  Stamens  5,  alternate  with  the  petals.  Ovary 
i -celled,  with  2  parietal  placentae.  Styles  2,  distinct  or  united.  Fruit 
a  pulpy,  globose,  or  ovoid  berry,  bearing  the  remains  of  the  calyx  at  its 
summit. 

1.  Ribes  Cynosbati,  L.     (Gr.,  tynosbatos,  the  dog-thorn.)    WILD  GOOSEBERRY 
or  DOGBERRY.     Flowers  1-3.    Calyx  tube  ovoid-campanulate,  green.    Berry  beset 
with  awl-shaped  prickles.     In  rocky  woods. 

2.  Ribes    setosum,   Lindl.      (L.,  setosus,  bristly.)      BRISTLY  GOOSEBERRY. 
Flowers   1-4,   calyx  tubular  and  white.      Stem  with  numerous  prickles.     Fruit 
glabrous  or  only  sparingly  prickly.     In  thickets  and  along  lake  shores. 

3.  Ribes  gracile,   Michx.    (L.,  gracilis,  slender.)    MISSOURI  GOOSEBERRY. 
Flowers  about  3,  white  or  greenish,  drooping.     Lobes  of  the  calyx  longer  than  the 
tube.     Stamens  much  exserted.     Berry  reddish  purple.     In  rocky  or  dry  soil. 

4.  Ribes  oxycanthoides,  L.     (Gr.,  oxys,  sharp ;  akanthos,  spine ;  eidos,  resem- 
blance.)    HAWTHORN  or  NORTHERN  GOOSEBERRY.    Flowers  1-3  on  short  pedi- 
cels, greenish  purple  or  white.    Stamens   short,  not  exserted.      Stems  scarcely 
prickly.    Fruit  reddish  purple  when  ripe,   smooth.     In   low  grounds  or  damp 
woods. 

5.  Ribes  floridum,  L'Her.     (L.,  floridus,  flowery.)    WILD  BLACK  CURRANT. 
Leaves   somewhat  pubescent  and  resinous-dotted  beneath.      Flowers  many  in 
pendulous  racemes,  greenish  white.     Calyx  tube  cylindric.     Fruit  smooth,  black, 
and  globose-ovoid  when  ripe.     In  woods. 

6.  Ribes  rubrum,  L.     (L.,  ruber,  red.)    RED  CURRANT.    Without  prickles. 
Leaves  3~5-lobed  and  serrate.     Flowers  in  loose,  pendulous  racemes,  greenish  or 
purplish.     Calyx  tube  campanulate.    Stamens  short.    Fruit  red  and  smooth. 

7.  Ribes  cereum,  Dougl.     (L.,  cereus,  waxy.)     WHITE-FLOWERED  or  SQUAW 
CURRANT.     Flowers  sessile  or  on  short  pedicels  in  short  racemes,  from  the  same 
buds  as  the   rounded,  reniform   leaves,  whitish   or  greenish  white.    Calyx  tube 
tubular  and  glandular.     Fruit  red  and  insipid. 

8.  Ribes  aureum,  Pursh.    (L.,  aureus,  golden  yellow.)     GOLDEN,  BUFFALO, 


56  Introduction  to  Botany. 

or  MISSOURI  CURRANT.  Flowers  several  in  leafy-bracted  racemes,  yellow,  spicy- 
scented,  ^  to  i  inch  long.  Calyx  tube  cylindric,  about  3  times  as  long  as  the  lobes. 
Fruit  smooth,  yellow,  becoming  black.  Along  streams. 

ROSACES.     ROSE  FAMILY. 

Herbs,  trees,  or  shrubs  with  alternate,  mostly  stipulate,  leaves. 
Flowers  regular ;  sepals  5,  often  subtended  by  as  many  sepal-like 
bractlets ;  petals  5,  apparently  inserted  on  the  calyx ;  stamens  usually 
indefinite,  apparently  inserted  on  the  calyx  (expanded  border  of  the 
base  of  the  receptacle).  Pistils  i-many,  distinct  or  united.  Some  of 
our  most  beautiful  flowers  and  best  fruits  belong  to  this  family. 


Longitudinal  diagrams  of  type  flowers  of  the  Rosaceae.    At  plum; 
B,  rose ;   C,  strawberry. 

Ovary  superior  or  half  superior. 

Ripened  pistil  a  drupe  or  drupelet. 

Fruit  consisting  of  a  single  pistil.  PRUNUS  I. 

Fruit  consisting  of  several  pistils  cohering  over  an  elongated  receptacle.        RUBUS  IV. 
Ripened  pistil  a  few-  to  several-seeded  pod. 

Pistils  5-8;  pods  not  inflated.  SPIRAEA  II. 

Pistils  1-5;  pods  inflated.  PHYSOCARPUS  III. 

Ripened  pistil  an  achene. 

Carpels  distinct  and  numerous  on  a  convex  receptacle,  which  becomes  fleshy  and  edible 

in  fruit.  FRAGARIA  V. 

Carpels  distinct  on  a  dry  feceptacle;  styles  not  lengthening  in  fruit;  bracts  conspicuous 

at  the  sinuses  of  the  calyx.  POTENTILLA  VI. 

Carpels  2-6  on  a  short  receptacle;  styles  not  lengthening  in  fruit;  bracts  at  the  sinuses 

of  the  calyx  minute  or  wanting.  WALDSTEINIA  VII. 

Carpels  numerous  on  a  dry  conical  or  cylindrical  receptacle;  style  persisting  as  a  hairy 

or  jointed  tail  to  the  achene.  GEUM  VIII. 

Ovary  inferior. 

Pistils  several,  inclosed  in  an  urn-shaped  receptacle.  ROSA  IX. 

Pistil  single,  compound,  its  cells  as  many  as  the  styles  (2-5). 

Fruit  a  pome;  ovary  s-celled,  its  carpels  2-seeded.  PVRUS  X. 

Fruit  a  small,  berrylike  pome;  ovary  becoming  lo-celled,  its  carpels  2-seeded. 

AMELANCHIER  XI. 
Fruit  a  small,  drupelike  pome  with  1-5  bony  stones.  CRATVEGUS  XII. 


Dicotyledones.  57 


I.  PRUNUS.    Plum,  Cherry,  Peach. 

(The  ancient  Latin  name.) 

Trees  or  shrubs,  with  leaves  mostly  simple  and  serrate.  Flowers 
perfect ;  lobes  of  calyx  and  corolla  5  ;  ovary  superior  and  free  from 
the  so-called  calyx  tube  at  maturity.  Stamens  15-20;  pistil  i,  with  2 
pendulous  ovules.  Fruit  a  fleshy  drupe  with  a  hard  stone. 

1.  Prunus  Americana,  Marsh.    WILD  YELLOW  or  RED  PLUM.    Flowers  in 
lateral  umbels,  white,  appearing  before  the  leaves,  about  i  inch  broad.    Calyx 
lobes  entire  and  pubescent  within.     Leaves  ovate  or  obovate-acuminate,  nearly 
glabrous  when  mature.    Branches  somewhat  thorny.    Fruit  red  or  yellow,  globose, 
little  or  no  bloom ;  stone  slightly  flattened.    Shrubs  or  small  trees.    River  banks 
and  woods. 

2.  Prunus  Watsoni,  Sargent.     (Latin  genitive  of  proper  name.)     SAND  PLUM. 
A  somewhat  spiny  shrub,  6  to  10  feet  high.     Flowers  in  numerous  lateral  fascicles, 
about  5  inch  in  diameter.    Leaves  ovate  to  ovate-lanceolate,  finely  serrulate,  shining 
above.    Petals  oblong-obovate  and  short-clawed.    Globose  fruit  about  f  inch  in 
diameter,  no  bloom,  flesh  yellow.     In  sandy  soil. 

3.  Prunus  Chicasa,   Michx.     (Latinized  form  of  Chickasaw,  Indian  name.) 
CHICKASAW  PLUM.    A  small  tree  with  somewhat  thorny  branches.    Flowers  in 
lateral  umbels,  expanding  shortly  before  or  with  the  leaves.    Leaves  lanceolate  or 
oblong-lanceolate,  serrulate,  glabrous  when  mature.      Drupe  red,  5  to  |  inch  in 
diameter;  bloom  scant;  skin  thin;  stone  ovoid,  hardly  flattened.     In  dry  soil. 

4.  Prunus  Besseyi,  Bailey.      (Latin  genitive  of  proper  name.)     WESTERN 
SAND  CHERRY.    A  shrub,  i  to  4  feet  high.    Flowers  in  lateral  umbels,  expanding 
with  the  leaves,  \  to  nearly  \  inch  in  diameter.     Leaves  mostly  elliptic  or  oblong- 
elliptic.     Stipules  of  young  shoots  often  longer  than  the  short  petioles.     Fruit  black, 
mottled,  or  yellow,  5  to  §  inch  in  diameter,  astringent.     Branches  often  spreading 
and  prostrate.     Prairies. 

5.  Prunus  Persica,   Sieb.  &  Luce.     (L.,  persicus,  persian.)     PEACH.    Small 
trees.     Leaves  thin,  lanceolate,  serrate.     Fruit  large  and  edible ;  stone  thick-walled, 
somewhat  compressed,  deeply  wrinkled.    Flowers  pink,  about  £  inch  in  diameter; 
borne  in  clusters. 

6.  Prunus  Pennsylvania,  L.  f.    WILD  RED  CHERRY.    Small  tree.    Flowers 
on  long  pedicels,  many  in  a  corymbose  cluster.    Leaves  oval  or  lanceolate  on 
slender  petioles,  shining  on  both  sides,  serrulate,  unfolding  with  the  flowers.     Fruit 
small  and  globose,  with  thin  skin  and  sour  flesh,  light  red.     Stone  globular.     In 
rocky  woods. 

7.  Prunus  Virginiana,  L.    CHOKE  CHERRY.    A  shrub  2  to  10  feet  high. 
Flowers  in  racemes,  terminating  shoots  of  the  season.    Leaves  obovate  or  broadly 
oval,  sharply  serrulate  with  slender  teeth.    Drupe  red  or  nearly  black,  about  J  inch 
in  diameter,  very  astringent.    Stone  globular.    Along  river  banks. 


58  Introduction  to  Botany. 

8.  Prunus  serbtina,  Ehrh.  (L.,  serotinus,  late  ripe.)  WILD  BLACK  CHERRY. 
Large  tree.  Flowers  in  racemes,  terminating  leafy  branches.  Leaves  thick,  oval 
to  oval-lanceolate.  Drupe  dark  purple  or  black,  about  \  inch  in  diameter,  some- 
what astringent,  but  sweetish  and  pleasant.  In  woods. 

n.  SPIRffiA.    Meadowsweet. 

(Gr.,  speirao,  to  twist;  from  the  spiral  pods  of  some  species.) 

Shrubs  or  perennial  herbs,  with  simple,  pinnatifid,  or  pinnate  leaves 
and  white  or  rose-colored  flowers  in  corymbs  and  panicles.  Calyx 
5-cleft,  short,  and  campanulate.  Petals  5,  inserted  on  the  calyx. 
Stamens  10-60.  Pods  5-8,  not  inflated,  few  to  several-seeded. 

1.  Spiraea  corymbosa,  Raf.     (Gr.,  korym'bos,  a  cluster.)     CORYMBED  SPIRAEA. 
Shrub,  i  to  3  feet  high.     Leaves  oval  to  orbicular,  unequally  and  coarsely  serrate 
from  some  distance  above  the  base,  thick.     Flowers  in  terminal  corymbs,  white, 
about  $  inch  broad.     Pods  glabrous.     Mountains  and  rocky  places. 

2.  Spiraea  salicifolia,  L.     (L.,  salix,  willow ;  folium,  leaf.)     WILLOW-LEAVED 
or  COMMON  MEADOWSWEET.     An  erect  shrub,  2  to  4  feet  high.    Leaves  oval, 
obovate,   or    oblanceolate,    sharply  serrate   above  the   middle;    nearly  glabrous 
throughout.    Flowers  in  dense  terminal  panicles.     Flowers  white  or  tinged  with 
pink,  about  J  to  £  inch  broad.     In  swamps  or  moist  grounds. 

3.  Spiraea  lobata,  Jacq.     (Gr.,  lobos,  a  lobe.)     QUEEN  OF  THE  PRAIRIE. 
Perennial  herb,  -2  to  8  feet  tall.     Leaves  interruptedly  3~7-foliate  ;  leaflets  3~5-lobed 
or  parted  and  unequally  serrate  or  incised ;  terminal  leaflet  y-o-parted ;  the  lower 
leaves  sometimes  3  feet  long.     Stipules  persistent  and  serrate.     Flowers  pink  or 
purple,  fragrant,   borne   in   a  panicle  on   a  long,  naked  peduncle.     Pods  5-8 
i-2-seeded.     Moist  ground  and  prairies. 

4.  Spiraea  Ariincus,  L.     (L.,  aruncus,  beard  of  a  goat.)     GOAT'S  BEARD. 
Smooth,  tall,  perennial  herb  with  2-3-pinnate,  large  leaves  on  long  petioles;  leaflets 
ovate  to  lanceolate,  sharply  doubly  serrate.    Flowers  small,  whitish,  and  dioecious 
in  panicled,  slender  spikes.     Pods  3-5,  several-seeded,  pedicels  reflexed  in  fruit. 
In  rich  woods. 

III.  PHYSOCARPUS.    Nine-bark. 

(Gr.,physa,  a  bladder;  karpos,  fruit.) 

Branching  shrubs  with  palmately  lobed  leaves,  and  white  flowers  in 
umbel-like  corymbs.  Carpels  1-5,  inflated;  stamens  30-40.  In  other 
respects  like  Spircea. 

i.  Physocarpus  opulifolius,  Maxim.  (L.,  opulus,  a  kind  of  maple;  folium, 
leaf.)  NINE-BARK.  Shrub,  3  to  10  feet  high  with  recurved  branches,  the  bark 
peeling  off  in  thin  strips.  Leaves  petioled,  ovate-orbicular,  3-lobed,  serrate,  i  to  2 
inches  long,  or  longer  on  young  shoots.  Corymbs  terminal,  peduncled,  nearly 


Dicotyledones.  59 

spherical,  many-flowered,  i  to  2  inches  across.     Flowers  white  or  purplish.     Pods 
purplish  and  conspicuous.     River  banks  and  rocky  places. 


IV.  RUBUS.    Bramble.    Raspberry.    Blackberry. 

(The  Roman  name,  allied  to  L.,  ruber,  red.) 

Herbs,  shrubs,  or  trailing  vines.  Calyx  without  bractlets,  5-parted. 
Petals  5  ;  stamens  numerous.  Carpels  several,  seldom  few,  on  a  convex 
or  elongate  receptacle,  ripening  into  drupelets  and  forming  an  aggregate 
fruit.  Flowers  usually  white,  sometimes  pink  or  purple,  and  fruit  edible. 

1.  Rubus  strigosus,  Michx.     (L.,  strigosus,  lean  or  thin.)     WILD  RED  RASP- 
BERRY.     Biennial  shrubby  stems,  3  to  6  feet  high,  densely  covered  with  weak, 
glandular  bristles,  or  hooked  prickles  on  the  older  stems.      Leaves  3-5-foliate, 
leaflets  ovate  or  ovate-oblong.     Inflorescence  both  terminal  and  axillary.    Flowers 
white,  3  to  5  inch  broad ;  petals  and  sepals  about  equal,  both  spreading.    Fruit  light 
red,  elongate-hemispheric.    Hills  and  thickets. 

2.  Rubus  occidentalis,  L.     (L.,  occidentalis,  western.)     BLACK  RASPBERRY. 
THIMBLEBERRY.     Stems  canelike  and  recurved,  sometimes  as  much  as  12  feet 
long,  decidedly  glaucous,  and  sparingly  beset  with  small,  hooked  prickles.     Leaves 
mostly  3-foliate,  serrate,  and  somewhat  incised,  white-pubescent  beneath.     Inflores- 
cence usually  terminal,  compact-corymbose.     Fruit  purple  black,  hemispheric. 

3.  Rubus  triflorus,  Richardson.     (L.,  fri,  three ;  fas,  floris,  flower.)     DWARF 
RASPBERRY.    Stems  6  to  18  inches  long,  trailing  or  ascending,  somewhat  pubescent, 
and  without  prickles.    Leaves  pedately  or  pinnately  3-foliate,  sometimes  5-foliate. 
Flowers  1-3  on  slender,  glandular-pubescent  peduncles;   sepals  reflexed.      Fruit 
red  purple.    Swamps  or  wooded  hillsides. 

4.  Rubus  hispidus,  L.     (L.,  hispidus,  bristly.)     RUNNING  SWAMP  BLACK- 
BERRY.     Stems  slender  and  creeping,  slightly  woody,  beset  with  weak  bristles; 
erect  or  ascending  branches,  4  to  12  inches  long,  with  few  or  no  prickles.     Leaves 
of  3,  rarely  5   obovate,  obtuse,  unevenly  serrate  leaflets.     Flowers  racemose  and 
axillary  or  terminal,  5  to  §  inch  in  diameter.     Fruit  composed  of  a  few  drupelets, 
small,  black,  and  sour,  remaining  on  the  receptacle.     In  low  woods  or  swamps. 

5.  Rubus  trivialis,  Michx.    (L,.,  trivialis,  common.)    LOW-BUSH  BLACKBERRY. 
Stems  several  feet  long,  trailing  or  procumbent,  bristly  and  prickly.     Leaves  mostly 
3-foliate,  coriacious  and  evergreen,  nearly  or  quite  glabrous.     Peduncles  prickly, 
i-3-flowered.    Flowers  about  i  inch  broad.    Sepals  reflexed,  much  shorter  than  the 
petals.    Fruit  black,  sometimes  i  inch  long,  pleasant,  remaining  on  the  receptacle. 
In  sandy  soil. 

6.  Rubus  Canadensis,  L.      LOW-RUNNING  BLACKBERRY  or   DEWBERRY. 
Stems  shrubby,  becoming  several  feet  long,  and  trailing,  naked  or  with  scattered 
prickles.    Leaves  3-y-foliate,  leaflets  ovate  to  ovate-lanceolate.    Flowers  few,  termi- 
nal, and  racemose  or  solitary;  peduncles  leafy.     Fruit  delicious,  sometimes  i  inch 
long,  remaining  on  the  receptacle.    In  dry  soil. 


60  Introduction  to   Botany. 

V.  FRAGARIA.    Strawberry. 

(L.,fraga,  strawberry.) 

Acaulescent,  perennial  herbs,  propagating  by  runners.  Leaves 
3-foliate,  basal,  and  tufted,  on  long  petioles  with  a  sheathing  mem- 
branous stipule.  Flowers  on  erect,  naked  scapes,  corymbose  or 
racemose,  polygamo-dioecious.  Sepals  5-bracteolate,  persistent,  deeply 
5-lobed.  Petals  5,  obovate,  clawed,  white.  Stamens  numerous.  Car- 
pels numerous,  on  an  elongated  receptacle  which  becomes  fleshy  and 
edible  in  fruit ;  carpels  becoming  dry  achenes. 

1.  Fragaria  Virginiana,  Duchesne.    VIRGINIA  or  SCARLET  STRAWBERRY. 
Leaflets  thick,  broadly  oval  or  obovate ;  petioles  2  to  6  inches  long ;  inclined  to  be 
villous-pubescent  with  spreading  or  appressed  hairs.    Fruit  ovoid,  red,  the  achenes 
imbedded  in  pits.    Scape  shorter  than  the  leaves.     In  fields  or  woodlands. 

2.  Fragaria  vesca,  L.     (L.,vescas,  small  or  thin.)     EUROPEAN  WOOD  STRAW- 
BERRY.    Leaflets  thick,  broadly  oval  or  ovate,  usually  not  so  villous  as  the  pre- 
ceding.    Scapes  longer  than  the  leaves,  and  the  fruit  lifted  above  them.     Fruit 
hemispheric  or  conic,  red,  achenes  not  imbedded  in  pits.     Fields  and  rocky  places. 

VI.  POTENTILLA.    Cinquef oil  or  Five-finger. 

(L. ,  potens ,  powerful,  from  reputed  medicinal  value  of  one  of  the  species.) 

Herbs,  rarely  shrubs.  Leaves  digitately  or  pinnately  compound, 
alternate,  stipulate.  Flowers  perfect,  cymose  or  solitary.  Calyx  usually 
5-lobed,  subtended  by  as  many  bractlets.  Petals  mostly  5,  often  emar- 
ginate,  yellow,  white,  or  purple.  Stamens  usually  many,  sometimes  5-10. 
Carpels  numerous,  on  a  dry  receptacle  which  is  often  hairy. 

1.  Potentilla  arguta,  Pursh.    (L.,  argutus,  sharp,  pungent.)    TALL  or  GLANDU- 
LAR ClNQUEFOlL.    Flowers  white,  cymose.     Stout  and  erect,  i  to  4  feet  high. 
Basal  leaves  with  7-11  leaflets,  long-petioled.    Stem  leaves  shorter  with  fewer  leaflets. 
Leaflets  cut-serrate.    Flowers  white,  about  ?  inch  broad,  in  terminal  cymes.    Plant 
glandular-pubescent. 

2.  Potentilla  argentea,  L.      (L.,  argenteus,  silvery.)      SILVERY  or  HOARY 
ClNQUEFOlL.     Flowers  yellow,  cymose.    Stems  ascending,  tufted,  4  to  12  inches 
long,  white  from  woolly  pubescence.     Leaves   digitately  5-foliate,  the   divisions 
lanciniate  beyond  the  middle,  green  above,  white  beneath.     In  dry  soil. 

3.  Potentilla  Norvegica,  L.    ROUGH  CINQUEFOIL.    Flowers  yellow  in  termi- 
nal cymes.    Erect  and  stout  annuals  or  biennials  with  rough  pubescence,  6  inches 
to  2  feet  or  more  high.     Leaves  3-foliate,  the  lower  petioled,  upper  stem  leaves 
nearly  or  quite  sessile.    Leaflets  obovate  to  oblong-lanceolate.    Styles  glandular- 
thickened  at  the  base.     In  dry  soil. 

4.  Potentilla  leucocarpa,  Rydberg.     (Gr.,  leukos,  white ;  karpos,  fruit.)     DIP- 


Dicotyledones.  61 


FUSE  CiNQUEFOlL.  Flowers  yellow  in  loose,  leafy  cymes.  Diffuse,  rather  weak 
annual,  6  inches  to  3  feet  high.  Leaves,  all  but  the  uppermost,  3-foliate  and  peti- 
oled.  Leaflets  thin,  oblong,  incisely  serrate.  Styles  thickened  below.  In  damp 
soil. 

5.  Potentilla  Anserina,   L.     (L.,  anserinus,  pertaining  to  geese.)     SILVER- 
WEED.     Flowers  yellow,  solitary  and  axillary.     Herbaceous  and  tufted,  spreading 
by  slender   runners.     Leaves   pinnate;    leaflets  7-25,  oblong  to  obovate,  serrate, 
white-pubescent  beneath.    Style  filiform.     River  banks,  lake  borders,  etc. 

6.  Potentilla   Canadensis,    L.      COMMON    CINQUEFOIL   or   FIVE-FINGER. 
Flowers  yellow,  solitary  and  axillary.    Stems  tufted,  and  spreading  by  slender 
runners.    Leaves  digitately  5-foliate,  sometimes  3-4-foliate,  petioled.    In  dry  soil. 

VH.  WALDSTEINIA. 

(Named  for  Francis  von  Waldstein.) 

Perennial  herbs  resembling  the  strawberry,  but  with  yellow  flowers 
and  2-6  carpels  inserted  on  a  short  receptacle.  Flowers  corymbose  on 
bracted  scapes.  Petals  conspicuous  and  stamens  numerous. 

i,  Waldsteinia  fragarioides,  Tratt.  (L.,/raga,  strawberries ;  Gr.,  eidos,  resem- 
blance.) BARREN  OR  DRY  STRAWBERRY.  Leaves  on  long  petioles,  tufted, 
mostly  3-foliate;  leaflets  obovate-cuneate,  dentate,  crenate,  or  incised.  Scapes 
corymbosely  3-8-flowered;  pedicels  slender  and  sometimes  drooping.  Wooded 
hillsides. 

VHI.  GEUM.    Avens. 

(Ancient  Latin  name.) 

Perennial  herbs,  with  pinnatifid  or  odd  pinnate,  stipulate  leaves ; 
basal  leaves  clustered,  stem  leaves  smaller.  Calyx  somewhat  campanu- 
late,  5-lobed,  usually  with  5  bractlets  at  the  sinuses.  Petals  5,  exceed- 
ing the  calyx.  Stamens  many,  inserted  on  the  disk  below  the  calyx. 
Carpels  many,  on  an  elevated,  dry  receptacle.  Styles  persisting  in  the 
form  of  hairy,  naked,  or  jointed  tails  to  the  achenes. 

1.  Geum  rivale,  L.     (L.,  rivalis,  belonging  to  a  brook.)     PURPLE  or  WATER 
AVENS.     Flowers  purple  and  nodding,  calyx  lobes  erect  or  spreading.     Erect,  i  to 
3  feet  high,  pubescent.     Basal  leaves  lyrately,  interruptedly  pinnate;  stem  leaves 
3-lobed  or  3-pinnate.     Achenes  very  pubescent ;  style  jointed,  and  plumose  below. 
In  wet  meadows  and  swamps. 

2.  Geum  ciliatum,  Pursh.     (L.,  cilium,  an  eyelash.)     LONG-PLUMED  PURPLE 
AVENS.     Flowers  light  purple ;  styles  very  long  and  plumose  throughout.     Scapose, 
pubescent  herbs,  6  to  18  inches  tall.    Scapes  3-8-flowered.    Basal  leaves  tufted, 
pinnate,  leaflets  very  numerous  and  cut-toothed.     In  rocky  soil. 

3.  Geum  album,  Gmel.     (L.,  albus,  white.)     WHITE  AVENS.     Flowers  white, 
less  or  more  than  5  inch  broad.     Plants  softly  pubescent  or  nearly  glabrous,  15  to 


62      .  Introduction  to   Botany. 

z\  feet  high.  Basal  leaves  3-foliate  or  pinnately  divided,  the  terminal  lobe  larger 
and  broadly  ovate.  Stem  leaves  3~5-lobed  or  divided,  nearly  or  quite  sessile. 
Receptacle  densely  bristly,  and  styles  glabrous,  or  pubescent  below.  In  shady 
places. 

4.  Geum  Virginianum,  L.    ROUGH  AVENS.    Resembling  the  preceding  species, 
but  stouter  and  bristly  pubescent.     Flowers  creamy  white.     Receptacle  glabrous  or 
merely  downy.    Low  grounds  and  borders  of  woods. 

5.  Geum  macrophyllum,  Willd.     (Gr.,  makros,  large ;  phyllon,  leaf.)     LARGE- 
LEAVED  AVENS.     Flowers  yellow.    Basal  leaves  lyrate-pinnate,  the  terminal  lobe 
much  exceeding  the  others.     Lateral  lobes  3-6,  with  smaller  lobes  interspersed. 
Upper  leaves  of  2-4  leaflets.    Receptacle  glabrous;    style  slender  and  jointed, 
pubescent  below.    Stems  erect  and  bristly-pubescent. 


IX.  ROSA.    Rose. 

(L.,  rosa,  rose.) 

Erect  or  climbing,  generally  prickly,  shrubs.  Flowers  showy,  red, 
pink,  or  white,  rarely  yellow.  Lobes  of  the  calyx  usually  5  ;  petals  5  ; 
stamens  many,  all  borne  around  the  margin  of  an  urn-shaped  receptacle, 
in  which  are  inclosed  numerous  carpels,  arising  from  the  base.  Fruit 
berrylike,  consisting  of  the  thickened,  hollow  receptacle  and  inclosed 
carpels. 

1.  Rosa  setigera,  Michx.     (L.,  seta,  bristle;  gerere,  to  bear.)     CLIMBING  or 
PRAIRIE  ROSE.     Stems   climbing,  becoming  several  feet  long,  beset  with  stout, 
scattered  prickles.     Leaflets   commonly  3,   sometimes   5.     Stipules   very  narrow. 
Styles  cohering  in  a  column.     Fruit  globular  and  somewhat  glandular.     Prairies 
and  thickets. 

2.  Rosa  blanda,  Ait.     (L.,  blandus,  of  a  smooth  tongue,  agreeable.)     SMOOTH 
or  MEADOW  ROSE.    Erect,  2  to  4  feet  tall,  almost  destitute  of  prickles.    Leaflets 
5-7;  stipules  rather  broad.    Styles  separate,  fruit  globose  or  pyriform,  nearly  or 
quite  glabrous,  tipped  by  the  persistent,  long,  erect,  or  spreading  sepals.     In  moist 
and  rocky  places. 

3.  Rosa  Arkansana,  Porter.    ARKANSAS  ROSE.    Erect,  i  to  2  feet  high,  the 
stems  beset  with  slender  bristles.     Leaflets  7—11.     Lanceolate  sepals  persistent, 
spreading,  or  reflexed.     Fruit  globose  and  glabrous.     Prairies. 

4.  Rosa  Woodsii,  Lindl.     (Latin  genitive  of  proper  name.)     WOODS'  ROSE. 
i  to  3  feet  high.    Straight  spines  on  the  stems,  at  least  below.     Leaflets  5-9. 
Acuminate,  lanceolate  sepals  erect  on  the  globose  fruit.    Usually  with  spines  just 
below  the  stipules.     Prairies. 

5.  Rosa  humilis,  Marsh.     (L.,  kumilis,  low.)     Low  or  PASTURE  ROSE.    From 
i  to  6  feet  high,  bushy.     Leaflets  mostly  5,  sometimes  7 ;  straight  spines  below  the 
stipules.     Flowers  solitary  or  few  together.     Sepals  deciduous,  spreading,  com- 
monly lobed.     In  dry  and  rocky  soil. 


Dicotyledones.  63 

X.  PYRUS.    Pear  and  Apple. 

(L.,/z>wj,  a  pear  tree.) 

Trees  or  shrubs,  with  conspicuous  flowers  in  corymbed  cymes. 
Receptacle  (in  this  instance  commonly  called  the  calyx  tube)  urn- 
shaped,  fleshy,  and  adherent  to  the  carpels.  Sepals,  or  lobes  of  the 
calyx,  5  ;  petals  5  ;  stamens  numerous.  Styles  2-5  ;  carpels  2-5,  their 
walls  of  cartilaginous  texture,  ovules  2  in  each  cavity.  Fruit,va  pome 
or  berrylike. 

1.  Pyrus  communis,  L.     (L.,  communis,  common.)     COMMON  PEAR.    Bark 
smooth,  branches  apt  to  have  somewhat  thorny  spurs.     Leaves  ovate  with  small 
teeth.     Flowers  pure  white.     Fruit  tapering  toward  the  base ;  flesh  containing  grit 
cells.     Native  of  Europe  and  Asia. 

2.  Pyrus  Malus,  L.     (L.,  malum,  an  apple.)     COMMON  APPLE.    Trees  with 
spreading  branches.     Leaves  broadly  ovate  or  oval,  rounded,  or  subcordate  at  the 
base.     Flowers  pink  or  white;  calyx  tomentose.    Fruit  15  to  3  inches  in  diameter. 
Native  of  Europe  and  Western  Asia. 

3.  Pyrus   coronaria,   L.      (L.,  coronarius,  pertaining  to  a  wreath  or  crown.) 
AMERICAN    CRAB    APPLE.     A    small    tree.    Leaves  ovate  to  triangular-ovate, 
sharply  serrate,  and  frequently  somewhat  lobed,  rounded  or  somewhat  cordate 
at  the  base.     Flowers  rose-colored  and  very  fragrant.    Styles  woolly  and  united 
below.     Fruit  very  acid,  greenish  yellow,  fragrant.     In  thickets. 

4.  Pyrus  angustifdlia,  Ait.     (L.,  angustus,  narrow ;  folium,  leaf.)     NARROW- 
LEAVED  CRAB  APPLE.    A  small  tree.    Leares  oval  to  oblong-lanceolate,  commonly 
ovate-lanceolate  and  narrowed  at  the  base,  dentate  or  entire.     Flowers  pink  and 
fragrant.     In  thickets. 

5.  Pyrus  loensis,   Bailey.      (Latinized  form,  meaning  pertaining  to   Iowa.) 
WESTERN  CRAB  APPLE.     Resembling  Pyrus  coronaria,  but  the  leaves  are  white- 
pubescent  on  the  lower  surface,  oval  or  ovate,  usually  narrowed  at  the  base.    Fruit, 
dull  green  with  small  light  dots.     In  thickets. 

6.  Pyrus  Japonica,  Thunb.     (Latinized  form,  signifying  relating  to  Japan.) 
JAPAN   QUINCE.    A   cultivated,  thorny,  and   much-branched  shrub  from  Japan. 
Flowers  scarlet  red,  produced  in  great  abundance  before  the  leaves.     Leaves  oval 
or  wedge-oblong.    Fruit  hard  and  green  ;  speckled. 

XI.  AMELANCHIER.    Juneberry.    Service  Berry.    Shad  Bush. 

.    (Savoy  name  of  the  medlar.) 

Shrubs  or  small  trees,  with  solitary  or  racemose  white  flowers  and 
simple,  petioled,  serrate  leaves.  Calyx  campanulate  and  more  or  less 
adnate  to  the  ovary,  with  5  narrow,  reflexed,  persistent  lobes.  Styles 
2-5,  cavities  of  the  ovary  becoming  twice  as  many,  with  I  ovule  in  each 
cavity.  Pome  small  and  berrylike,  4-io-celled. 


64  Introduction  to   Botany. 

1.  Amelanchier  Canadensis,  T.  &  G.    SHAD  BUSH  or  SERVICE  BERRY.    A 
tree,  seldom  more  than  25  feet  high,  with  ovate  or  ovate-lanceolate  leaves,  acute  or 
acuminate  at  the  apex,  and  rounded  or  cordate  at  the  base.    Flowers  in  spreading 
or  drooping  racemes,  pedicels  long  and  slender.    Bracts  and  stipules  long,  silky- 
ciliate.     The  sweet  pome  globose,  red  or  purple.     In  dry  woodlands. 

2.  Amelanchier  rotundifdlia,   Rcem.      (L.,  rotundus,    round;    folium,    leaf.) 
ROUND-LEAVED  JUNEBERRY.    Similar  to  the  above,  but  with  leaves  ovate  to 
orbicular,  and  more  or  less  rounded  at  both  ends.     In  woods  and  thickets. 

3.  Amelanchier  alnifdlia,  Nutt.     (L.,  alnus,  alder;  folium,  leaf.)     NORTH- 
WESTERN JUNE  or  SERVICE  BERRY.    Shrub  3  to  8  feet  high.    Leaves  elliptic  to 
orbicular,  serrate  above  the  middle.    Flowers  in  short,  dense  racemes.    A  bloom 
on  the  purple,  globose  pome.     In  dry  soil. 


XH.  CRATAEGUS.    Hawthorn  or  White  Thorn. 
(Gr.  kratos,  strength,  referring  to  the  toughness  of  the  wood.) 

Thorny  shrubs  or  small  trees.  White  or  pink  flowers  in  terminal, 
corymbose  clusters.  Leaves  simple  and  often  lobed.  Receptacle  (so- 
called  calyx  tube)  cup-shaped,  adherent  to  the  1-5  carpels.  Sepals  or 
calyx  lobes  5  ;  petals  5 ;  stamens  numerous.  Pome  small  and  drupe- 
like  with  1-5  i -seeded  stones. 

1.  Crataegus  Crfls-galli,  L.     (L.,  crus,  leg;  galli,  genitive  of  gallus,  a  cock.) 
COKSPUR  THORN.    Shrub  or  small  tree,  with  obovate  or  oblanceolate,  serrate 
leaves,  glabrous,  shining  above  and  dull  beneath.     Stems  with  slender  thorns, 
which  are  2  to  4  inches  long.    Fruit  globular  and  red.     In  thickets. 

2.  Crataegus  coccinea,  L.    (L.,  coccineus,  of  a  scarlet  color.)    SCARLET  THORN 
or  HAW  or  RED  HAW.    Shrub  or  small  tree,  with  stout  spines  i\  to  2  inches  long. 
Leaves  broadly  ovate  or  orbicular,  truncate  or  subcordate  at  the  base,  sharply 
incised  and  serrate,  with  glandular-tipped  teeth.     Glandular  pubescence  on  the 
calyx  and  pedicels.    Red,  globular  fruit  about  \  inch  in  diameter,  sometimes 
more.     In  thickets. 

3.  Crataegus  mdllis,  Scheele.     (L.,  mollis,  soft.)     RED-FRUITED  THORN  or 
HAW.     Similar  to  Crat&gus  coccinea,  but  with  leaves  sometimes  5  inches  long, 
usually  very  pubescent  beneath,  and  hairy  fruit,  sometimes  i  inch  in  diameter.    In 
thickets. 

4.  Crataegus  flava,  Ait.    (L.,  flavus,  golden  yellow.)    SUMMER  or  YELLOW 
HAW.    Small  and  often   quite  thorny  tree.    Leaves  obovate,  often  obtuse  and 
glandular-dentate  at  the  apex,  narrowed  at  the  base,  at  first  pubescent  on  both 
sides.    Fruit  globose  to  pyriform,  yellow,  red,  or  greenish.     In  sandy  thickets. 

5.  Crataegus  Oxyacdntha,  L.    ENGLISH  HAWTHORN.    Shrubs  or  trees,  with 
stout  and  frequent  thorns.     Leaves  generally  broadly  ovate  or  obovate,  sharply 
3~7-lobed,  broadly  cuneate  at  the  base,  i  to  2  inches  long.     Flowers  sometimes 
more  than  i  to  2  inches  in  diameter,  white  or  pink.    Fruit,  deep  red,  globose  or 
ovoid.    Roadsides  and  thickets. 


Dicotyledones.  65 


LEGUMINOS^.    PULSE  FAMILY. 

Herbs,  trees,  or  shrubs,  with  papilionaceous  or  more  or  less  irregular 
flowers,  and  alternate,  stipulate,  pinnately  or  palmately  compound 
leaves.  Stamens  usually  10,  monadelphous,  diadelphous,  or  some- 
times distinct.  Ovary  superior,  of  a  single  carpel,  and  becoming  a 
legume  in  fruit. 

Herbs. 

Stamens  distinct.  BAPTISIA  I. 

Stamens  diadelphous,  or  sometimes  all  united  near  the  base. 

Leaves  palmately  3-foliate.  TRIFOLIUM  II. 

Leaves  odd-pinnate.  ASTRAGALUS  VI. 

Leaves  abruptly  pinnate.  VICIA  VII. 

Herbs  or  sometimes  shrubs. 

Stamens  distinct  or  united  only  at  the  base. 

Leaves  bipinnately  compound;  stamens  8-12.  SCHRANKIA  XI. 

Leaves  bipinnately  compound;  stamens  10-5.  DESMANTHUS  XII. 

Stamens  monadelphous  or  diadelphous.  PSORALEA  III. 

Trees  or  shrubs. 

Stamens  distinct  or  united  only  at  the  base. 
Leaves  once  or  twice  pinnately  compound. 

Trees  without  thorns.  GYMNOCLADUS  IX. 

Trees  with  conspicuous  thorns.  GLEDITSCHIA  X. 

Leaves  simple.  CERCIS  VIII. 

Stamens  monadelphous;  leaves  odd-pinnate.  AMORPHA  IV. 

Stamens  diadelphous;  leaves  odd-pinnate.  ROBINIA  V. 


I.  BAPTISIA.    False  Indigo. 
(Gr.,  baptisis,  dipping  or  dyeing.) 

Erect,  perennial  herbs,  with  palmately  3-foliate  or  rarely  simple 
leaves.  Flowers  yellow,  white,  or  blue,  truly  papilionaceous,  borne  in 
racemes.  Stamens  10  and  distinct;  ovary  stipitate,  and  pod  inflated. 
Standard  about  equaling  the  wings  and  keel,  its  sides  reflexed. 

1.  Baptisia  tinctoria,  R.  Br.     (L.,  tinctorius,  pertaining  to  dyeing.)     WILD 
INDIGO.     Erect,  glabrous,  2  to  4  feet  high.    Leaves  3-foliate,  the  leaflets  obovate 
or  oblanceolate,  petioles  short.    Flowers  yellow.     Pods  raised  on  a  stipe  longer 
than  the  calyx,  and  tipped  with  the  awl-shaped  style.     In  dry  soil. 

2.  Baptisia  leucophaea,   Nutt.     (Or.,  leukos,  white;  phaios,  gray.)     LARGE- 
BRACTED  WILD   INDIGO.    About   i   foot  high,  with  divergent  branches,  pubes- 
cent throughout.    Leaves  3-foliate,  sessile,  or  short-petioled;   leaflets  spatulate  or 
oblanceolate,  with  ovate  or  lanceolate,  persistent  stipules.      Flowers  white  or  cream 
color,  about  i   inch  long,  borne  in  a  many-flowered  raceme,  which  sometimes 
becomes  i  foot  long.     Pods  hoary,  pointed  at  both  ends.     On  prairies. 


66  Introduction  to  Botany. 

II.  TRIFOLIUM.    Clover  or  Trefoil. 

(L.,  trit  three;  folium,  leaf.) 

Herbs,  with  mostly  slender  branches  and  3-foliate  leaves,  the  leaflets 
denticulate.  Flowers  pink,  purple,  white,  or  yellow,  papilionaceous. 
Stamens  10,  diadelphous,  or  sometimes  all  united  near  the  base. 
Flowers  in  heads  or  spikes,  and  pods  straight  and  membranaceous. 

1.  Trifolium  pratense,   L.     (L.,  pratensis,  growing  in  a  meadow.)     RED  or 
MEADOW  CLOVER.    Flowers  red  purple,  sessile,  in  globose  or  ovoid  heads,  the 
heads  nearly  or  quite  sessile.    Somewhat  pubescent,  branching,  perennial  herbs. 
Leaflets  short-stalked  from  the  same  point,  often  dark-spotted  near  the  middle.     In 
fields  and  meadows. 

2.  Trifolium  repens,  L.     (L.,  repens,  creeping.)     WHITE  CLOVER.    Creeping, 
mostly  glabrous  perennials,  rooting  at  the  nodes.    Leaves  rising  on  long  petioles ; 
leaflets  obovate,  emarginate-denticulate.    Flowers  white,  in  globose  heads  borne 
on  long  peduncles;  flowers  of  the  head  raised  on  pedicels.    In  fields  and  open 
places. 

HI.  PSORALEA. 

(Gr.,psoraleos,  scurfy,  alluding  to  glandular  dots  of  the  leaves.) 

Herbs  or  shrubs,  with  1-5 -foliate,  glandular-dotted  leaves.  Flowers 
bluish  purple  or  white,  borne  mostly  in  spikes  or  racemes.  Calyx 
5-cleft,  the  lower  lobe  longest.  Stamens  diadelphous,  sometimes 
monadelphous.  Ovary  i-ovuled;  the  short  pod  ovoid  and  indehiscent. 

1.  Psoralea  tenuiflora,  Pursh.     (L.,  tennis,  slender,  small ;  flos,  floris,  flower.) 
FEW-FLOWERED  PSORALEA.    Erect  and  slender,  2  to  4  feet  high,  hoary  with  an 
appressed  pubescence.     Leaves  short-petioled,  digitately  3-5-foliate,  mostly  oblong- 
oval  or  elliptic  or  obovate,  sometimes  mucronate  at  the  apex.     Peduncles  slender 
and  much  exceeding  the  leaves,  loosely  6-i4-flowered.    Corolla  purplish ;  corolla 
about  twice  the  length  of  the  calyx.     Prairies. 

2.  Psoralea  argophy^lla,  Pursh.     (Gr.,  argos,  white;  phyllon,  leaf.)     SILVER- 
LEAF  PSORALEA.     Silvery  pubescent  with  white  appressed  hairs,     i  to  3  feet  tall. 
Petioles  about  equaling  the  leaves.    Leaflets  3-5,  digitate,  oblong-oval  to  oblong- 
obovate.      Inflorescence  interrupted-spicate,  peduncles  much  exceeding  the  leaves. 
Flowers  deep  blue  or  purplish,  about  J  inch  long.    Calyx  lobes  lanceolate,  very 
densely  pubescent.     Pod  ovate,  with  a  straight  beak.    On  prairies. 

3.  Psoralea  floribunda,  Nutt.     (l^,.,Jlos,floris,  flower  +  adjectival  ending,  signi- 
fying plenty.)     MANY-FLOWERED  PSORALEA.    Stems  much  branched,  i  to  4  feet 
high,  hoary,  not  glandular.    Leaves  mostly  3-5-foliate,  sometimes  y-foliate.   Leaflets 
oblong,  canescent  beneath  and  glandular  on  both  surfaces.     Peduncles  2  to  7  inches 
long,  usually  many-flowered.    Lobes  of  the  calyx  triangular-acute.    Prairies. 

4.  Psoralea  esculenta,  Pursh.     (L.,  esculentus,  edible.)     POMME  BLANCHE. 


Dicotyledones.  67 

PRAIRIE  APPLE  or  TURNIP.  4  to  18  inches  high  from  a  tuberous  root.  Densely 
hairy  all  over.  Leaves  digitately  5-foliate.  Leaflets  mostly  obovate  or  obovate- 
oblong.  Peduncles  often  longer  than  the  petioles,  bearing  dense,  oblong,  spikelike 
racemes.  Calyx  nearly  equaling  the  bluish  corolla.  Prairies. 

IV.  AMORPHA.    False  Indigo. 

(Gr.,  amorphos,  deformed,  from  the  absence  of  4  petals.) 

Shrubs,  with  odd-pinnate,  glandular-punctate  leaves.  Flowers  mostly 
violet  or  purple.  Corolla  consisting  of  the  standard  alone,  the  wings 
and  keel  wanting.  Stamens  10,  monadelphous  below,  anthers  all  alike. 
Pod  i-2-seeded. 

i.  Amorpha  fruticbsa,  L.  (L.,  fruticosus,  shrubby.)  FALSE  INDIGO.  A 
rather  tall  shrub.  Leaflets  11-21,  elliptic  to  oblong.  Flowers  dense  in  solitary  or 
clustered  spicate  racemes.  Standard  violet-purple.  River  banks  and  hillsides. 

2.  Amorpha  microphylla,  Pursh.  (Gr.,  mikros,  small  ;  phyllon,  leaf.)  FRA- 
GRANT FALSE  INDIGO.  A  bushy  shrub,  scarcely  exceeding  i  foot  in  height, 
nearly  glabrous.  Standard  purplish.  Flowers  fragrant;  racemes  mostly  solitary. 
Prairies. 

V.  ROBINIA.    Locust  Tree. 
(Named  for  John  Robin,  herbalist  to  Henry  IV.  of  France.) 

Trees  or  shrubs,  with  odd-pinnate  leaves  and  racemes  of  showy 
flowers.  Stipules  often  spiny.  Calyx  5-toothed,  the  2  upper  teeth 
somewhat  united.  Standard  broad  and  reflexed.  Stamens  diadel- 
phous.  Ovary  several-ovuled.  Pods  linear  and  flat,  becoming  mar- 
gined on  the  seed-bearing  edge. 

i.  Robinia  Pseudacacia,  L.  (Gv.^pseudcs,  false  +  acacia.)  COMMON  LOCUST 
TREE  or  FALSE  ACACIA.  Becoming  a  large  tree.  Leaflets  9-19;  stalked,  ovate 
or  oval.  Stipules  often  spiny.  Flowers  white  and  fragrant  in  loose,  drooping 
racemes.  Twigs,  petioles,  and  pods  glabrous.  Extensively  planted. 


vi.  ASTRAGALUS. 

(Ancient  Greek  name  of  a  leguminous  plant.) 

Chiefly  perennial  herbs,  with  odd-pinnate  leaves  and  flowers  in 
racemes.  Stamens  diadelphous  with  the  anthers  all  alike.  Calyx 
tubular,  the  teeth  nearly  equal.  Standard  narrow  and  the  keel  of  the 
corolla  blunt.  Pod  somewhat  turgid,  the  sutures  often  projecting  so  as 
to  divide  the  cavity  into  two. 

i.  Astragalus  caryocarpus,  Ker.  (Gr.,  katyon,  a  nut  ;  karpos,  fruit.)  GROUND 
PLUM.  Flowers  violet-purple,  about  |  inch  long,  in  short  racemes.  Pods  globose 


68  Introduction  to  Botany. 

or  oval,  sessile,  short-pointed,  glabrous,  fleshy,  2-celled,  sometimes  i  inch  in  diame- 
ter. Branches  6  to  15  inches  long,  ascending  or  decumbent.  Leaflets  15-25, 
mostly  oblong-elliptic.  Peduncles  equaling  or  shorter  than  the  leaves.  Plant 
covered  with  a  pale,  minute,  appressed  pubescence.  Prairies. 

2.  Astragalus  Mexicanus,  A.  DC.    LARGER  GROUND  PLUM.    Corolla  cream 
color,  purplish  at  the  tip,  about  I  inch  long.     Globose,  glabrous  pods  sometimes 
exceeding  i  inch  in  length,  pointless,  2-celled.    Pubescence  somewhat  spreading. 
Leaflets  17-33,  oblong  to  obovate.     Prairies. 

3.  Astragalus  gracilis,  Nutt.    (L.,gracilis,  slender.)    SLENDER  MILK  VETCH. 
Flowers  purple,  £  inch  or  less  in  length,  in  slender,  spikelike  racemes.     Pendent 
pods  i-celled,  concave  on  the  back,  at  first  hoary,  but  becoming  glabrous.     Plants 
erect  and  slender,  i  to  2  feet  high,  finely  pubescent.    Leaflets  11-21,  distant  and 
narrowly  linear.    Prairies. 

VII.  VICIA.    Vetch  or  Tare. 

(The  classical  Latin  name.) 

Herbaceous  vines,  climbing  or  trailing.  Leaves  evenly  pinnate  and 
tendril-bearing.  Stipules  mostly  half-sagittate.  Calyx  teeth  5,  about 
equal,  or  the  2  upper  shorter.  Standard  obovate  or  oblong,  emargi- 
nate;  wings  adhering  to  the  middle  of  the  keel.  Stamens  more  or  less 
diadelphous,  9  and  i.  Style  slender,  hairy  at  the  summit. 

1.  Vicia  Americana,  Muhl.    AMERICAN  VETCH  or  PEA  VINE.    Flowers  bluish 
purple,  somewhat  less  than  i  inch  long,  3-9  in  a  loose-flowered  raceme.     Mostly 
glabrous  perennial,  2  to  3  feet  long.     Leaflets  8-14,  elliptic  or  ovate-oblong,  con- 
spicuously veined.     Pod  glabrous,  4-y-seeded.     In  moist  soil. 

2.  Vicia  linearis,  Green.     (L.,  linearis,  linear.)     Flowers  and  fruit  as  in   Vicia 
Americana,  but  the  leaflets  are  narrowly  linear,  and  the  branches  are  weak  and 
often  zigzag.     In  dry  soil. 


VIII.  CERCIS.    Redbud  or  Judas  Tree. 

(Ancient  name  of  the  Oriental  Judas  tree.) 

Shrubs  or  small  trees,  with  red  purple  flowers  in  umbellike  clusters 
along  last  year's  twigs  or  older  branches,  appearing  just  before  the 
leaves.  Leaves  simple,  broad,  and  heart-shaped.  Standard  in  the  bud 
inclosed  by  the  wings.  Stamens  10  and  distinct.  Pods  oblong  and 
flat. 

i.  Cercis  Canadensis,  L.  REDBUD.  A  small  tree,  often  planted  for  ornamental 
purposes.  In  rich  soil. 


Dicotyledones.  69 

IX.  GYMNOCLADUS.    Kentucky  Coffee  Tree. 
(Gr.,  gymnos,  naked  ;  klados,  branch,  alluding  to  the  somewhat  naked  branches.) 

Trees  with  bipinnate  leaves  and  regular,  dioecious,  or  polygamous, 
whitish  flowers  in  terminal  racemes.  Calyx  tubular,  5-lobed;  petals 
usually  5,  oblong  or  oval,  inserted  at  the  summit  of  the  calyx  tube; 
stamens  10,  distinct,  shorter  than  the  petals.  Pod  oblong,  2-valved, 
thick  and  leathery,  pulpy  between  the  seeds. 

i.  Gymnocladus  Canadensis,  Lam.  KENTUCKY  COFFEE  TREE.  Becoming 
a  large  tree  with  rough  bark.  The  bipinnate  leaves  quite  large,  of  7-15  leaflets,  the 
leaflets  mostly  ovate,  acuminate,  i  to  3  inches  long.  Racemes  many-flowered. 
Pods  5  to  10  inches  long.  Rich  woods. 

X.  GLEDITSCHIA.    Honey  Locufet. 

(Named  for  J.  G.  Gleditsch,  botanist.) 

Becoming  large,  thorny  trees.  Leaves  evenly  once  or  twice  pinnate. 
Flowers  small,  greenish,  in  slender,  axillary  racemes,  polygamous. 
Calyx  campanulate,  3-5-cleft;  petals  3-5,  inserted  on  the  summit  of 
the  calyx  tube;  stamens  6-10,  distinct.  Pod  flat,  i -many-seeded. 

i.  Gleditschia  triacanthos,  L.  (Gr.,  tri,  three;  akantha,  thorn.)  THREE- 
THORNED  ACACIA  or  HONEY  LOCUST.  Stems  often  armed  with  numerous  stout, 
simple,  or  branching  thorns.  Leaflets  oval  to  oblong-lanceolate,  about  i  inch  long. 
Pod  i  foot  or  more  long,  shining  and  twisted,  many-seeded ;  a  sweet  pulp  between 
the  seeds.  Woods  and  pastures. 

XI.  SCHRANKIA.    Sensitive  Brier. 
(Named  for  F.  P.  Schrank,  botanist.) 

Perennial  herbs  or  shrubs,  prostrate  or  procumbent,  with  bipinnate 
leaves,  which  are  somewhat  sensitive,  the  leaflets  small  and  numerous. 
Flowers  perfect  or  polygamous,  borne  in  axillary,  peduncled  heads  or 
spikes.  Calyx  5-toothed,  minute ;  petals  united  to  the  middle,  5-cleft 
above;  corolla  pink  or  purple.  Stamens  8-12,  distinct  or  united  at  the 
base.  Plant  beset  with  recurved  prickles.  Pods  spiny,  linear,  acute,  or 
acuminate. 

i.  Schrankia  uncinata,  Willd.  (L.,  uncinatus,  barbed.)  SENSITIVE  BRIER. 
Herbaceous  perennial,  branches  decumbent,  2  to  4  feet  long,  very  prickly.  Stems 
grooved  and  angled.  Pinnae  4-8  pairs.  Leaflets  obliquely  elliptic,  8-15  pairs, 
prominent  elevated  veins  beneath.  Heads  very  dense,  globose.  Flowers  pink. 
In  dry  soil. 


7O  Introduction  to   Botany 


XII.  DESMANTHUS. 

(Gr.,  desma,  a  band;  anthos,  flower.) 

Perennial  herbs  or  shrubs,  with  bipinnate  leaves  and  small,  regular, 
greenish,  or  whitish  flowers  in  peduncled,  axillary  heads  or  spikes,  per- 
fect or  polygamous.  Calyx  campanulate,  5-toothed.  Petals  5  and  dis- 
tinct or  slightly  coherent  below.  Stamens  10  or  5,  distinct,  exserted. 
Pod  flat,  several-seeded. 

i.  Desmanthus  brachylobus,  Benth.  (Gr.,  brachys,  short ;  lobos,  lobe.)  Stems 
i  to  3  feet  high,  ascending  or  erect,  nearly  or  quite  glabrous.  Pinnae  6-15  pairs. 
Leaflets  20-30  pairs.  Stamens  5.  Pods  curved,  oblong,  or  lanceolate,  in  globose 
heads.  Prairies  and  river  banks. 


GERANIACE.®.    GERANIUM  FAMILY. 

Chiefly  herbs,  with  perfect  and  mostly  symmetrical  flowers.  Parts 
of  the  flower  usually  in  5's.  Stamens  commonly  as  many  or  twice  as 
many  as  the  sepals,  often  5  long  and  5  short.  Ovary  5-lobed  and 
5 -celled.  Axis  of  the  dry  fruit  persisting. 


I.  GERANIUM.    Cranesbill. 

(Gr.,geranos,  a  crane,  from  fancied  resemblance  of  the  long  carpels  to  a  beak  of  the  crane.) 

Herbs  with  palmately  lobed,  parted,  or  divided  leaves,  and  flowers 
on  axillary  i -few-flowered  peduncles.  Stamens  10,  5  long  and  5  short. 
Sepals  and  petals  5,  imbricated  in  the  bud.  Ovary  5-lobed  and  5-celled, 
beaked  by  the  compound  style;  ovules  2  in  each  cavity.  Carpels 
breaking  away  from  the  central  axis  in  dehiscence. 

1.  Geranium  maculatum,  L.     (L.,  maculatus,  spotted.)    WILD  or  SPOTTED 
CRANESBILL.     Perennials  with   a  thick  rootstock.     i  to  2  feet  high,  branching 
above ;  pubescent,  with  more  or  less  spreading  hairs.     Basal  leaves  long-petioled, 
deeply  3~5-parted.     Stem   leaves  shorter,  but  similar.     Petals  \  inch  long,  light 
purple,  bearded  on  the  claw.    Sepals  hairy  and  awn-pointed.    Carpels  pubescent. 
Woods. 

2.  Geranium  Carolinianum,  L.    CAROLINA  CRANESBILL.    Annuals,  6  to  15 
inches  high,  branched  from  the  base,   diffuse,  loosely  pubescent.    Leaves  5-9- 
parted,  the  divisions  cleft  into  somewhat  linear  lobes.     Flowers  whitish  or  pale 
rose,  in  compact  clusters;  peduncles  and  pedicels  short  and  hairy.     Beak  of  the 
hispid-pubescent  ovary  nearly  i  inch  long.     In  barren  soil  and  waste  places. 


Dicotyledones.  71 


H.  OXALIS.    Wood  Sorrel. 

(Gr.,  oxys,  sour,  relating  to  the  sour  juice.) 

Herbs  with  sour  juice;  leaves  radical  or  alternate,  mostly  of  3  obcor- 
date  leaflets.  Sepals  5  and  persistent;  petals  5,  somewhat  united  at 
the  base.  Stamens  10,  alternately  longer  and  shorter,  mostly  mona- 
delphous  at  the  base.  Ovary  5-lobed  and  5-celled,  the  carpels  dehis- 
cing on  the  back.  Styles  5  and  distinct.  Seeds  2  or  more  in  each 
cell.  Flowers  often  dimorphous  or  trimorphous  (see  Botany,  page  176). 

1.  Oxalis  violacea,  L.     (L.,  violaceus,  violet-colored.)     VIOLET  WOOD  SOR- 
REL.     Perennial,  acaulescent  herbs  from  a  scaly  bulb,  4  to  9  inches  high.     Scapes 
umbellately  several-flowered,  mostly  exceeding  the  leaves.     Petals  rose-violet,  rarely 
white.    Open  woods  or  rocky  places. 

2.  Oxalis  stricta,  L.    (L.,  strictus,  close,  tight.)    UPRIGHT  YELLOW  WOOD 
SORREL.    Annual  or  perennial.     Commonly  branching  at  the  base,  the  branches 
spreading,  about  6  inches  long.    Stems  leafy  to  the  top ;  flowers  yellow.     In  woods 
and  fields. 

RUTACE^.    RUE  FAMILY. 

Mostly  trees  or  shrubs.  Leaves  usually  compound.  Flowers  in  our 
species  dioecious  or  polygamous.  Sepals  and  petals  3-5  ;  stamens  as 
many  or  twice  as  many  as  the  sepals.  Pistils  2-5,  distinct,  or  as  many 
carpels  united  to  form  a  compound  ovary.  Fruit  usually  a  capsule. 
Plants  secrete  a  pungent  and  acrid  volatile  oil;  the  foliage  dotted  with 
pellucid  glands. 

I.  XANTHOXYLUM.    Prickly  Ash. 

(Gr.,  xanthos,  yellow;  xylon,  wood.) 

Trees  or  shrubs.  Leaves  alternate,  odd-pinnately  compound.  The 
small  whitish  or  greenish  flowers  dioecious,  cymose,  axillary,  or  termi- 
nal. Sepals  and  petals  4-5.  Stamens  4  or  5.  Pistils  2-5,  united  only 
by  their  styles.  Stems,  and  often  the  petioles,  prickly.  Pods  fleshy, 
2-valved,  i-2-seeded. 

i.  Xanthoxylum  Americanum,  Mill.  PRICKLY  ASH  or  TOOTHACHE  TREE. 
Shrub  with  yellowish  green  flowers  appearing  before  the  leaves.  Flowers  in  sessile, 
axillary,  umbellate  clusters.  Leaves  odd-pinnate,  leaflets  ovate,  5-11.  Bark,  leaves, 
and  pods  very  pungent-aromatic.  In  woods  and  thickets. 


Introduction  to   Botany. 


EUPHORBIACEJE.    SPURGE  FAMILY. 

Herbs,  sometimes  shrubs  or  trees,  with  milky  secretions.     Flowers 
monoecious   or  dioecious.     Flowers   mostly  apetalous,  and   sometimes 

much  reduced  and  subtended  by  an 
involucre,  which  resembles  a  calyx. 
Stamens  few  to  many,  filaments  some- 
times united.  Ovary  usually  3-celled, 
with  1-2  ovules  in  each  cavity.  Fruit 
usually  a  3-lobed  capsule,  dehiscing 
elastically  when  mature.  (Fig.  349.) 

I.  EUPHORBIA.    Spurge. 

(Named  for  Euphorbus,  physician  to  King  Juba.) 

Flowers  without  a  calyx  and  clus- 
tered in  a  cup-shaped,  calyxlike  invo- 
lucre, the  cluster  easily  mistaken  by  the 
beginner  for  a  single  flower.  The 
flowers  of  two  kinds  within  the  invo- 
lucre, many  staminate  flowers  consist- 
ing of  a  single  stamen,  and  a  single 
pistillate  flower  consisting  of  a  single 
3-lobed  pistil  protruding  above  the 
staminate  flowers.  Styles  3  and  stig- 
mas 6. 


Diagrams  of  the  inflorescence  of  a 
Euphorbia,  i,  a  single  inflores- 
cence with  petal-like  involucre  and 
protruding  pistillate  flower.  2,  a 
staminate  flower  and  accompany- 
ing bract,  which  is  supposed  to  rep- 
resent the  calyx.  3,  longitudinal 
diagram  of  an  inflorescence,  show- 
ing the  pistillate  and  four  stami- 
nate flowers.  4,  cross  diagram  of 
an  inflorescence,  showing  the 
ovary  of  the  single  pistillate  flower 
surrounded  by  staminate  flowers. 
Around  all  there  is  the  involucre. 


i.  Euphorbia  serpens,  H.  B.  K.  (L.,  ser- 
pens,  creeping.)  ROUND-LEAVED  SPREAD- 
ING SPURGE.  Annuals,  branching  from  the 
base,  the  branches  prostrate,  slender,  2  to  12 
inches  long.  Leaves  orbicular,  ovate,  or  oval, 
often  less  than  \  inch  long,  less  than  twice  as 
long  as  broad.  Stipules  triangular  and  mem- 
branaceous.  In  open  places. 

2.  Euphorbia  corollata,  L.     (L.,  corolla,  a  little  crown.)     FLOWERING  SPURGE. 
Perennials  from  stout  rootstocks,   I  to  3  feet  tall,  umbellately  branched  above. 
Leaves  ovate,  lanceolate,  or  linear,   only  the   uppermost  opposite   or  whorled. 
Involucre  with  showy  white  appendages  appearing  like  petals.     In  dry  soil. 

3.  Euphorbia  marginata,  Pursh.     (L.,  marginatus,  provided  with  a  border.) 


Dicotyledones.  73 

WHITE-MARGINED  SPURGE.  Erect  annuals  with  stout  stems  from  i  to  3  feet  high. 
Bracts  of  the  involucre  white-margined  and  petallike.  The  uppermost  leaves  op- 
posite or  whorled  and  with  conspicuous  white,  petallike  margins.  In  dry  soil. 


ANACARDIACEJE.    SUMAC  FAMILY. 

Shrubs  or  small  trees,  with  acrid,  resinous,  or  milky  secretions, 
mostly  alternate  leaves,  and  perfect  or  polygamo-direcious  flowers. 
Calyx  3-7-cleft,  most  frequently  5 -cleft,  and  petals  when  present  of  the 
same  number.  Stamens  usually  as  many  or  twice  as  many  as  the 
petals.  Ovary  i-celled  and  i-ovuled.  Styles  1-3.  Fruit  generally  a 
small  drupe.  Sometimes  poisonous. 

I.  RHUS.    Sumac. 

(The  old  Greek  and  Latin  name.) 

Shrubs  or  trees,  with  alternate,  odd-pinnate,  3-foliate,  or  simple 
leaves.  Flowers  mostly  polygamous  in  axillary  or  terminal  panicles. 
Calyx  5-parted,  and  petals  5.  Stamens  5,  inserted  between  the  lobes 
of  a  flattened  disk  at  the  base  of  the  calyx.  Fruit  generally  a  small, 
dry  drupe. 

1.  Rhus.  trilobata,  Nutt.     (Gr.,  tri,  three ;  lobos,  lobe.)     ILL-SCENTED  SUMAC 
or  SKUNK  BUSH.    Shrub  2  to  6  feet  high,  mostly  glabrous.     Leaves  3-foliate,  the 
leaflets  sessile  or  nearly  so,  5  to  i  inch  long,  few  lobed  or  incised  toward  the 
summit.    Flowers  yellow  green,  in  clustered  spikes,  appearing  before  the  leaves. 
Unpleasantly  scented.     Rocky  hillsides. 

2.  Rhus  aromatica,  Ait.     (Gr.,  aromatikos,  pertaining  to  spice.)     (R.  Canaden- 
sts,  Marsh.)     FRAGRANT  or  SWEET-SCENTED  SUMAC.     Similar  to  the  preceding 
species,  but  the  leaflets  2  to  4  inches  long  and  pleasantly  aromatic,  and  crenate  or 
dentate  above  the  middle.     Rocky  hillsides. 

3.  Rhus  radicans,  L.     (L.,  radicans,  having  roots.)      (R.  Toxicodendron  in 
Gray's  "  Manual.")     POISON  IVY  or  POISON  OAK.      Woody;  climbing  trees,  etc., 
by  means  of  adventitious  rootlets.     Sometimes  shrubby  and  not  climbing.     Leaves 
3-foliate,  leaflets  i  to  4  inches  long,  the  terminal  longer  stalked  than  the  lateral 
leaflets.     Flowers  green  in  loose,  axillary  panicles.     In  thickets  and  low  grounds. 

4.  Rhus  hirta,  Sudw.    (L.,  hirtus,  hairy.)    STAG-HORN  SUMAC.     Large  shrub 
or  small  tree.     Leaves  pinnate,  with   11-31   leaflets.     Leaves   and  twigs  with  a 
velvety  pubescence.     In  dry  and  rocky  soil. 

5.  Rhus  glabra,  L.    (L.,glaber,  bald.)    SMOOTH  or  SCARLET  SUMAC.    Shrub 
or  small  tree.    Leaflets  11-31.    Foliage  and  twigs  glabrous  and  somewhat  glaucous. 
In  dry  soil. 


74  Introduction  to  Botany. 


SAPINDACEJE.     SOAPBERRY  FAMILY. 

Trees  or  shrubs,  with  simple  or  compound  leaves.  Flowers  mostly 
unsymmetrical  and  often  irregular.  Sepals  and  petals  4-5.  Stamens 
5-10,  inserted  in  a  fleshy  disk.  Ovary  2-3-lobed,  with  as  many  cells. 
Ovules  1-2  in  each  cell. 

I.  ACER.    Maple. 

(Latin  name  of  the  maple.) 

Mostly  trees,  with  palmately  lobed,  opposite  leaves  and  small, 
polygamo-dioecious  flowers.  Calyx  usually  5 -lobed  or  parted;  petals 
of  the  same  number  or  wanting.  Stamens  3-12.  The  2-celled  ovary 
with  a  pair  of  ovules  in  each  cell.  Styles  2,  stigmatic  along  their  inner 
surfaces.  Fruit,  2  diverging,  long- winged  samaras,  joined  together  at 
their  bases. 

1.  Acer  dasycarpum,  Ehrh.     (Gr.,  dasys,  dense  or  thick;  karpos,  fruit.)     SIL- 
VER, SOFT,  or  WHITE  MAPLE.    Becoming  large  trees.    Leaves  (white  and  some- 
what pubescent  beneath)  deeply  5-lobed,  4  to  6  inches  long,  the  lobes  irregularly 
dentate.    Flowers  greenish  or  reddish,  in  dense,  sessile,  lateral  clusters,  appearing 
before  the  leaves.     Petals  none.     Ovary  woolly  when  young.    Along  streams, 

2.  Acer  saccharinum,  Wang.     (Gr.,  sakckaron,  cane  or  palm  sugar.)     SUGAR 
or  ROCK  MAPLE.    Large  trees,  whose  sap  yields  most  of  the  maple  sugar  of  com- 
merce.    Leaves  3-y-lobed,  with  rounded   sinuses,  pale  beneath  and  dark  green 
above.    Flowers  in  lateral  or  terminal  corymbs  on  long,  slender,  drooping,  hairy 
pedicels,  appearing  with  the  leaves.     In  rich  woods. 

3.  Acer  Negiindo,  L.     (New  Latin  for  a  native  name.)     Box  ELDER  or  ASH- 
LEAVED  MAPLE.     (Negundo  aceroides,  Mcench,  in  Gray's  "  Manual.")     Trees  with 
pinnately  3~5-foliate  leaves.    Flowers  dioecious,  appearing  shortly  before  the  leaves, 
greenish  in  drooping  clusters.     Along  streams. 


H.  STAPHYLEA.    Bladder  Nut. 

(Gr.,  staphyle,  a  cluster.) 

Upright  shrubs,  with  opposite,  3-foliate,  or  pinnate  leaves  and  pani- 
cles or  racemes  of  white  flowers  terminating  branchlets  of  the  current 
season.  Lobes  of  the  5-parted  calyx  erect  and  whitish ;  petals  5, 
inserted  on  the  margin  of  a  thick  disk  at  the  base  of  the  calyx.  Sta- 
mens 5,  alternating  with  the  petals.  Carpels  3,  united  along  their  inner 
faces,  and  forming  in  fruit  a  3-lobed  and  3-celled  pod,  membranous  and 
inflated. 


Dicotyledones.  75 

i.  Staphylea  trifolia,  L.  (L.,  tri,  three ;  folium,  leaf.)  AMERICAN  BLADDER 
NUT.  Branching,  6  to  15  feet  high.  Leaflets  mostly  3,  ovate-acuminate.  Flowers 
white,  campanulate.  Carpels  in  fruit  separate  at  the  summit  and  dehiscing  along 
their  inner  margins.  In  moist  woods  and  thickets. 

m.  AESCULUS.    Horse-chestnut  or  Buckeye. 

(Latin  name  of  an  oak  tree.) 

Trees  or  shrubs.  Leaves  opposite,  palmately  3~9-foliate.  Flowers 
in  terminal  panicles.  Calyx  unequally  5-lobed  or  cleft.  Petals  4-5, 
unequal.  Stamens  usually  7,  filaments  slender  and  often  unequal. 
Ovary  3-celled  with  2  ovules  in  each  cell.  Style  slender.  Fruit,  a 
leathery  3-celled  and  3-seeded  capsule;  sometimes  2  seeds  become 
abortive.  Seeds  large  with  thick  and  shining  coat ;  scar  of  the  seed 
large  and  pale. 

1.  ^sculus  glabra,  Willd.    (L.,glaber,  without  hair.)     FETID  or  OHIO  BUCK- 
EYE.    Trees.     Leaflets  5-7,  mostly  5 ;  3  to  6  inches  long.     Flowers  pale  yellow,  in 
loose,  pubescent  panicles.    Woods  and  river  banks. 

2.  ./Esculus  arguta,  Buckl.     (L.,  argutus,  fiery.)     SHRUBBY  or  WESTERN 
BUCKEYE.    Shrub,  3  to  10  feet  high.    Leaflets  7-9,  narrow,  3  to  4  inches  long. 
Flowers  yellow  with  reddish  center,  in  dense  panicles.     Along  streams  and  in 
moist  woods  and  thickets. 

RHAMNACE^.    BUCKTHORN  FAMILY. 

Shrubs  or  small  trees,  sometimes  with  thorny  branches.  Leaves 
simple  and  alternate.  Flowers  small  and  sometimes  apetalous,  often 
polygamous,  and  in  some  instances  dioecious.  The  limb  of  the  obconic 
or  cylindric  calyx  tube  4-5 -toothed.  Petals  4-5,  inserted  on  the  calyx. 
Stamens  of  the  same  number  as  the  petals  and  inserted  with  and  oppo- 
site them.  Petals  more  or  less  concave  or  hooded  in  the  bud.  Ovary 
2-5 -celled,  with  i  ovule  in  each  cavity.  Stigmas  2-5.  Fruit,  a  drupe 
or  capsule,  often  3-celled. 

I.  RHA'MNUS.    Buckthorn. 

(The  ancient  Greek  name.) 

Shrubs  or  small  trees,  with  flowers  in  axillary  clusters,  greenish, 
polygamous,  and  dioecious.  Calyx  somewhat  urn-shaped,  lined  with 
a  fleshy  disk  below,  its  limb  4-5-toothed.  Petals  4-5,  or  none,  emargi- 
nate  and  hooded,  short-clawed.  Ovary  3-4-celled  and  free  from  the 
disk.  Drupe  berrylike,  containing  2-4  separate  nutlets. 


j6  Introduction  to   Botany. 

1.  Rhamnus  lanceolata,  Pursh.      (L.,  lanceolatus ,  armed  with  a  little  lance.) 
LANCE-LEAVED  BUCKTHORN.    A  tall  shrub  with  thornless  branches.    Leaves 
ovate-lanceolate,  short-petioled,  minutely  serrulate.     Greenish   flowers   in   groups 
of  2  or  3  in  the  axils  of  the  leaves.    Drupe  containing  2  grooved  nutlets.     In  dry 
soil. 

2.  Rhamnus  alnifolia,  L'Her.    (L.,  alnus,  alder ;  folium,  leaf.)    ALDER-LEAVED 
BUCKTHORN  or  DWARF  ALDER.    A  small  shrub  with  thornless  branches.    Leaves 
oval  to  elliptic,  serrated.     Flowers  greenish,  2  or  3  together  in  the  axils,  dioecious, 
without  petals,  appearing  with  the  leaves.     In  swamps. 

3.  Rhamnus  Caroliniana,  Walt.    CAROLINA  BUCKTHORN.    Thornless  shrub 
or  small  tree.    Leaves  broadly  oblong  or  oblong-elliptic.     Flowers  several  together 
in  axillary,  peduncled  umbels.     Petals  present.     Drupe  globose  and  sweet,  contain- 
ing 3  seeds.    In  swamps  and  along  rivers. 


H.  CEANOTHUS.    New  Jersey  Tea  or  Redwood. 

(Gr.,  keanothos,  a  kind  of  thistle.) 

Shrubs,  with  white,  blue,  or  yellow  flowers  in  axillary  or  mainly 
terminal,  clustered  umbels.  Calyx  mostly  hemispheric  and  5-lobed. 
Petals  5,  spreading,  incurved,  and  clawed.  Ovary  adnate  to  the  disk 
at  the  base  of  the  calyx,  3-lobed.  Style  short  and  3-cleft.  Fruit  3- 
lobed,  and  separating  at  maturity  into  3  nutlets. 

1.  Ceanothus   Americanus,  L.     NEW  JERSEY  TEA  or  REDROOT.     Stems 
ascending  or  erect,  generally  several  together  from  a  deep  reddish  root.     Leaves 
ovate  to  ovate-lanceolate,  finely  pubescent,  particularly  beneath.     Flowers  white. 
In  dry,  open  woods. 

2.  Ceanothus  ovatus,  Desf.     (L.,  ovatus,  egg-shaped.)     SMALLER  REDROOT. 
Similar  to  the  preceding  species,  but  the  leaves  are  oblong  or  oval-lanceolate,  and 
nearly  glabrous.    On  prairies  and  in  rocky  places. 


VITACE^I.    GRAPE  FAMILY. 

Woody  vines  trailing  or  climbing  mostly  by  tendrils.  Leaves  mostly 
palmately  lobed,  dentate,  or  compound.  Flowers  small  and  greenish, 
polygamous  or  dioecious.  Petals  4-5,  hypogynous  or  perigynous,  fall- 
ing away  without  expanding.  Limb  of  the  calyx  mostly  obsolete  or 
4~5-lobed.  Stamens  of  the  same  number  as  the  petals  and  opposite 
them.  The  single  ovary  often  immersed  in  a  fleshy  disk,  2-6-celled, 
with  1-2  ovules  in  each  cavity.  Fruit,  a  i-6-celled,  but  commonly 
2-celled  berry.  Stigma  slightly  2-lobed,  on  a  short  style  or  sessile. 


Dicotyledones.  77 


I.  VITIS.    Grape. 

(The  Latin  name.) 

Plants  climbing  high  by  coiling  tendrils.  Leaves  simple,  rounded, 
variously  sharply-incised,  and  lobed.  Flowers  polygamo-dicecious, 
sometimes  perfect,  borne  in  a  compound  thyrse.  Petals  falling  off 
without  expanding.  Five  nectariferous  glands  alternating  with  the 
stamens.  Fruit,  a  pulpy,  edible  berry. 

1.  Vitis  aestivalis,  Michx.     (L.,  cestivalis,  pertaining  to  summer.)     SUMMER 
or  SMALL  GRAPE.    Terete  branches  climbing  high.    Leaves  large,  dentate,  or  3-5- 
lobed ;  young  leaves  and  branches  quite  woolly.     Tendrils  and  flower  clusters  not 
present  opposite  each  third  leaf.     Berries  sour,  but  edible,  with  a  bloom.     In 
thickets. 

2.  Vitis  cinerea,  Englm.     (L.,  cinereus,  ashy.)     DOWNY  GRAPE.    Climbing. 
Branches  angled.     Leaves  entire   or   only  slightly  3-lobed,  dentate;    pubescence 
whitish  or  grayish,  especially  pronounced  on  the  under  side  of  leaf.     Berries  with- 
out bloom,  black,  edible,  somewhat  sour. 

3.  Vitis  riparia,  Michx.     (L.,  riparius,  relating  to  a  river  bank.)     RIVERSIDE 
or  SWEET-SCENTED  GRAPE.    Climbing  or  trailing.    Branches  only  slightly  angled 
or  rounded.     Plant  glabrous   throughout.      Leaves  shining,  mostly  sharply  3-7- 
lobed ;  stipules  %  to  \  inch  long,  persisting  until  the  fruit  is  formed.     Berries  bluish 
black,  with   a  bloom,  sweetish,  approaching  \   inch  in  diameter.    Along  rocky 
stream  banks  or  near  water. 

4.  Vitis   cordifblia,  Michx.     (L.,  cor,  cordis,  heart ;  folium,  leaf.)     FROST  or 
CHICKEN  GRAPE.     Climbing.    Branches  round  or  only  slightly  angled.     Leaves 
shining  above,  only  slightly  pubescent  beneath,  acuminate,  very  coarsely  serrate, 
sometimes  slightly  3-lobed,  cordate  at  the  base;  stipules  small.     Berries  black  and 
shining,  ripening  after  frost.     In  moist  thickets  and  along  streams. 


H.  AMPELOPSIS.    Virginia  Creeper. 

(Gr.,  ampelos,  a  vine;  opsis,  appearance.) 

Mostly  climbing,  woody  vines.  Leaves  digitately  3-5,  mostly  5- 
foliate.  Leaflets  oblong-lanceolate,  sparingly  serrate  above.  Tendrils 
with  clinging,  suckerlike  disks  at  their  tips. 

i.  Ampelopsis  quinquefolia.  (L.,  quinque,  five;  folium,  leaf.)  VIRGINIA 
CREEPER,  FALSE  GRAPE,  or  AMERICAN  IVY.  Climbing  high  on  trees  or  walls. 
Clinging  sometimes  by  rootlets  as  well  as  by  tendrils.  Flowers  in  panicles,  which 
are  spreading  in  fruit.  Berries  bluish.  In  woods  and  thickets.  Commonly  planted 
for  covering  walls. 


78  Introduction  to   Botany. 


TILIACE^.     LINDEN  FAMILY. 

Mostly  trees  or  shrubs.  Leaves  simple  and  generally  alternate,  with 
small,  deciduous  stipules.  Flowers  axillary  or  terminal,  cymose  or 
paniculate.  Sepals  mostly  5,  valvate.  Petals  of  the  same  number  as 
the  sepals,  sometimes  less  or  wanting,  mostly  valvate.  Stamens  many, 
5-io-adelphous.  Ovary  2-io-celled.  Styles  lobed  or  entire.  Pedun- 
cles springing  from  a  leaflike  expansion. 

I.  TILIA.    Linden  or  Basswood. 

(The  classical  Latin  name.) 

Trees,  with  serrate,  cordate,  somewhat  inequilateral  leaves,  and  white 
or  cream-colored  flowers.  Sepals  and  petals  5.  Stamens  many,  coher- 
ing in  5  sets  (5-adelphous) .  Ovary  5-celled  with  2  ovules  in  each  cell. 
Style  i  ;  stigma  5 -toothed.  Fruit,  1-2 -seeded,  drupaceous. 

1.  Tilia  Americana,  L.    BASSWOOD  or  AMERICAN  LINDEN.    A  large  tree. 
Leaves  2  to  5  inches  wide,  smooth  on  both  sides.    Flowers  fragrant  and  much 
visited  by  bees  for  nectar.    Along  river  bottoms. 

2.  Tilia  heterophylla,  Vent.    WHITE  BASSWOOD.    Leaves  whitened  beneath 
with  a  downy  pubescence.     In  mountainous,  wooded  districts. 

MALVACEJE.    MALLOW  FAMILY. 

Herbs  or  shrubs,  with  alternate  leaves  having  small,  deciduous 
stipules.  Flowers  mostly  perfect,  often  showy.  Sepals  mostly  5 
and  valvate,  somewhat  united  at  the  base.  Petals  of  the  same  number 
and  convolute  in  the  bud.  Stamens  many,  united  by  their  filaments 
around  the  pistil,  and  adherent  to  the  bases  of  the  petals.  Anthers 
i-celled.  Ovary  of  several  cells,  entire  or  lobed.  Styles  united  below, 
but  separate  above  and  usually  projecting  beyond  the  stamens. 

I.  MALVA     Mallow. 

(The  Latin  name.) 

Herbs.  Calyx  with  a  3-leaved  involucre  at  the  base.  Stamen-column 
bearing  anthers  only  at  the  summit.  The  numerous  styles  stigmatic 
along  the  inner  side.  Fruit  flattened  and  circular,  of  several  beakless 
I -seeded  carpels. 

i.  Malva  rotundif  lia,  L.  (L.,  rotitndns,  round;  folium,  leaf.)  RouND- 
LEAVED  or  RUNNING  MALLOW.  Procumbent  annual  or  biennial.  Leaves  round- 


Dicotyledones.  79 

reniform,  crenate,  with  5~9-rounded,  shallow  lobes.  Flowers  bluish  white,  clustered 
in  the  axils,  £  to  £  inch  broad.  Petals  about  twice  the  length  of  the  calyx  lobes. 
Waysides  and  cultivated  grounds. 

II.   CALLIRRHOE. 

(Gr.,  kalos,  beautiful;   rheo,  flower.) 

Herbs,  with  lobed  or  divided  leaves  and  showy  flowers.  Bracts  of 
the  involucre  when  present  1-3.  Calyx  5-parted;  petals  truncated  at 
their  apices,  as  many  as  the  lobes  of  the  calyx.  Stamen  column  anther- 
bearing  at  the  summit.  Carpels  about  10-20,  united  in  a  circle,  each 
i -seeded,  beaked  at  the  apex. 

1.  Callirrhoe  alcaeoides,  Gray.     (Gr., alkea, wild  mallow;  eidos,  form.)     LIGHT 
POPPY  MALLOW.     Erect  perennial,  8   to   20  inches  high  from  a  thickened  root. 
Basal  leaves  triangular  and  lobed ;  stem  leaves  digitately  divided.     Bracts  of  the 
involucre  none.    Flowers  pink  or  white,  about  i  inch  broad.    Carpels  pubescent. 
In  dry  soil. 

2.  Callirrhoe  digitata,  Nutt.     (L.,  digitatus,  having  fingers.)     FRINGED  POPPY 
MALLOW.    Similar  in   habit  to  the  preceding  species.     Flowers  i\  to  2  inches 
broad ;  petals  fimbriate  along  their  upper  margin ;  red  purple  to  white.    Carpels 
hardly  pubescent.     In  dry  soil. 

3.  Callirrhoe    involucrata,    Gray.      (L.,  involucrum,  a   wrapper.)      PURPLE 
POPPY  MALLOW.     Perennials,  i  to  2  feet  long,  procumbent  or  ascending  from  a 
deep  root.    Leaves  cordate-orbicular,  palmately  lobed  or  incised.    Bracts  of  the 
involucre  3.    Peduncle  slender  and  i-flowered.     Flowers  red  purple,  i  to  25  inches 
broad.    Carpels  rugose-reticulate.    In  dry  soil. 


VIOLACE^E.    VIOLET  FAMILY. 

Herbs,  with  irregular,  i -spurred  corolla  and  adnate  anthers  conniving 
over  the  ovary.  Ovary  i -celled  with  3  parietal  placentae.  Sepals  5  and 
petals  5.  Leaves  stipulate ;  flowers  nodding.  Style  club-shaped  with  a 
i -sided  stigma. 

I.  VIOLA.    Violet  or  Heart's-ease. 

(The  classical  Latin  name.) 

Herbs,  with  basal  leaves  commonly  clustered.  Flowers  usually 
scapose  and  solitary,  nodding,  often  of  two  kinds,  open  and  showy, 
and  cleistogamous  and  inconspicuous  beneath  the  leaves.  Sepals  more 
or  less  auricled.  Lower  petal  spurred  at  the  base,  and  the  two  lower 
anthers  with  spurlike  nectaries.  Capsule  dehiscing  into  3  valves. 


8o  Introduction  to  Botany. 


Acaulescent  from  a  rootstock. 

Flowers  various  shades  of  violet  and  purple  to  almost  white. 
Lateral  petals  bearded. 

(a-)  Outer  leaves  crenate-dentate,  inner  leaves  variously  palmately  lobed. 

VIOLA  PALMATA  I. 
(6)  Leaves  pedately  parted  into  linear,  obtuse  lobes.  VIOLA  PEDATIFIDA  II. 

(c)  Leaves  reniform  to  ovate-wedge-shaped,  cordate  at  the  base;  margins  crenate- 

dentate;  plants  glabrous.  VIOLA  CUCULLATA  III. 

(d)  Leaves   ovate   to  orbicular-ovate;    peduncles  and  other  parts  of  the   plant 

villous.  VIOLA  SOKAKIA  IV. 

Lateral  petals  beardless. 

(a)  Leaves  pedately  parted  or  divided.  VIOLA  PEDATA  V. 

(6)  Leaves  ovate  to  orbicular,  cordate  at  the  base,  crenate-margined,  sweet-scented. 

Cultivated.  VIOLA  ODORATA  VI. 

(c)  Leaves  lanceolate  to  linear-lanceolate.  VIOLA  LANCEOLATA  VII. 

Caulescent. 

Flowers  yellow. 

(a)  Leaves  reniform  to  broadly  ovate;  plant  villous  or  pubescent. 

VIOLA  PUBESCENS  VIII. 

(3)  Leaves  reniform  to  ovate,  only  slightly  pubescent;  stems  slender  or  decumbent. 

VIOLA  SCABRIUSCULA  IX. 
Flowers  various  shades  of  blue  or  violet  to  white,  rarely  yellowish. 

(a)  Leaves  ovate  to  nearly  orbicular,  acuminate  or  acute ;  stipules  ovate  to  lanceo- 

late and  entire.  VIOLA  CANADENSIS  X. 

(b)  Leaves  as  above,  but  stipules  dentate,  pinnatifid,  or  fimbriate. 

VIOLA  STRIATA  XI. 

(c)  Leaves  varying  from  nearly  orbicular  to  oblong-ovate  or  oblong-elliptic;  stip- 

ules large  and  leaflike,  pinnatifid  or  lyrate.  VIOLA  TRICOLOR  XII. 

(d)  Leaves,  etc.,  similar  to  the  above,  but  the  whole  plant  smaller  and  more  slender. 

VlOLA  TENELLA  XIII. 

1.  Viola  palmata,  L.     (L.,  palmatus,  hand-shaped.)     EARLY  BLUE  VIOLET. 
Acaulescent,  leaves  and  flowers  arising  from  a  rootstock  which  is  scaly  and  thick. 
Outer  and  lower  leaves  crenate-dentate,  inner   leaves   variously  palmately  lobed. 
Flowers  blue  of  different  shades,  sometimes  nearly  white.     Lateral  petals  bearded ; 
styles  beardless.     Mostly  in  woods. 

2.  Viola  pedatifida,   Don.     (L.,  pes,  pedis,  the  foot;   findo,  fidi,  to  divide.) 
PRAIRIE  VIOLET.    Acaulescent.     Leaves  and  flowers  from  a  short,  scaly  root- 
stock.    Leaves  pedately  parted  into  linear,  obtuse  lobes.     Flowers  bright  blue; 
lateral  petals  bearded.     On  prairies. 

3.  Viola  cucullata,  Ait.    (L.,  cucullus,  a  hood.)    MEADOW  or  HOODED  VIOLET. 
Acaulescent  from  a  thick,  scaly  rootstock.     Leaves  varying  from  reniform  to  ovate- 
wedge-shaped,  cordate  at  the  base,  crenate-dentate.    Flowers  blue,  varying  to  white ; 
lateral  petals  bearded.     Plants  glabrous,  or  only  slightly  pubescent  when  young. 
Common  in  various  habitats. 

4.  Viola  sororia,  Willd.     (L.,  sororius,  sisterly.)     WOOLLY  BLUE  VIOLET. 
Acaulescent  from  short  and  thick  rootstock.    'Leaves  mostly  ovate  or  orbicular- 
ovate,  pointed  at  the  apex  and  cordate  at  the  base.     Leaves  crenate-villous  when 
young,  but  becoming  less  so  with  age;  ascending.     Flowers  blue;  petals  more  or 
less  bearded.    Peduncles  villous.     Mostly  in  shady,  dry  soil. 


Dicotyledones. 


5.  Viola  pedata,  L.     (L^pedatus,  furnished  with  feet.)     BIRD'S-FOOT  VIOLET. 
Acaulescent  from  a  thick,  short  rootstock.     Leaves  pedately  parted  or  divided. 
Flowers  fragrant,  blue  to  violet,  opening  widely ;  petals  beardless.     Stigma  beard- 
less and  beakless.     On  hillsides  or  in  sandy  or  gravelly  soil. 

6.  Viola  odorata,  L.     (L.,  odoratus,  fragrant.)     SWEET  VIOLET.   'A  native  of 
Europe,  cultivated  in  gardens,  and  running  wild  in  some  localities.     Spreading  by 
stolons,  which  take  root  at  the  nodes.     Leaves  and  flowers  rising  from  a  thick 
rootstock.    Leaves  ovate  to  orbicular,  cordate  at  the  base,  crenate  on  the  margins. 
Flowers  mostly  blue,  varying  to  white ;  petals  beardless ;  fragrant. 

7.  Viola  lanceolata,  L.     (L.,  lanceolatus,  armed  with  a  little  lance.)     LANCE- 
LEAVED  VIOLET.    Acaulescent;    spreading  by  stolons,  with  root  at  the  nodes 
Leaves    and    flowers    from   a  slender   rootstock.      Leaves    lanceolate   to    linear- 
lanceolate,   gradually  tapering  to  a  petiole,  barely  crenate.     Flowers  white,  the 
lower  and  lateral  petals  purplish- veined,  beardless.    Along  streams  and  in  moist 
meadows. 

8.  Viola  pubescens,  Ait.     (L.,  pubescens,  hairy.)     HAIRY  YELLOW  VIOLET. 
Caulescent,  villous,  or  pubescent.      Basal   leaves   long-petioled,  withering  early. 
Upper  leaves  short-petioled.     Leaves  reniform   to   broadly  ovate,  finely  crenate- 
dentate.    Flowers  yellow,  purple-veined;  spur  short.     In  woods. 

9.  Viola  scabrisiicula,  Schwein.     (L.,  diminutive  adjective  from  scaber,  rough.) 
SMOOTHISH  YELLOW  VIOLET.     Resembling  the  preceding  species,  but  less  pubes- 
cent, and  stems  slender  and  sometimes  decumbent ;  basal  leaves  usually  persisting 
through  the  period  of  blossoming.     In  woods  and  thickets.     . 

10.  Viola  Canadensis,  L.    CANADA  VIOLET.    Caulescent.    Stems  tufted  and 
leafy  throughout.     Leaves  ovate,  sometimes  nearly  orbicular,  glabrous,  finely  cre- 
nate, acuminate,  or  acute.    Stipules  entire,  ovate  to  lanceolate.     Flowers  pale  violet 
to  white,  purple-veined.     In  woods  of  hills  or  mountains. 

11.  Viola  striata,  Ait.     (L.,  striatus,  furrowed.)     PALE  or  STRIPED  VIOLET. 
Similar  in  general  aspect  to  the  preceding  species,  but  the  stipules  are  dentate, 
pinnatifid,  or  fimbriate;  petals  cream-colored,  light  blue,  or  white,  much  veined. 
In  moist  woods  or  thickets. 

12.  Viola  tricolor,  L.     (L.ttri,  three;  color,  color.)     PANSY  or  HEART'S-EASE 
A  native  of  Europe,  cultivated  in  gardens,  and  sometimes  running  wild.     Rather 
stout  annuals  with  leafy  stems,  and  large,  leaflike,  pinnatifid,  or  lyrate  stipules. 
Flowers  large,  especially  in  cultivation,  variously  yellow,  purple,  blue,  violet,  and 
white. 

13.  Viola  tenella,  Muhl.     (L.,  tenellus,  somewhat  tender.)     FIELD  PANSY.    A 
native  annual  resembling  the  preceding  species,  but  the  plants  are  more  slender, 
stipules  smaller,  and  flowers  smaller.     In  woods  and  fields. 

ONAGRACEJE.    EVENING  PRIMROSE  FAMILY. 

Annuals  or  perennials,  mostly  herbaceous.  Flowers  axillary,  spicate, 
or  racemose.  Ovary  inferior,  the  so-called  calyx  tube  often  prolonged 
far  beyond  its  summit.  Calyx  usually  4-lobed,  sometimes  2-6-lobed. 


82  Introduction  to  Botany. 

Petals  usually  4,  sometimes  2-9,  convolute  in  the  bud.  Stamens  as 
many  or  twice  as  many  as  the  petals,  and  inserted  with  them  on  the 
tube  of  the  calyx.  Ovary  usually  4-celled ;  stigmas  2-4-lobed  or 
capitate.  Pollen  often  bound  together  by  cobwebby  threads. 

I.  (ENOTHERA.    Evening  Primrose. 
(Old  name  for  a  species  of  Eptlobium.) 

Calyx  tube  prolonged  beyond  the  ovary.  Petals  and  lobes  of  the 
calyx  4.  Lobes  of  the  calyx  reflexed.  Stamens  8,  the  anthers  mostly 
versatile.  Ovary  elongated  and  4-celled.  Pollen  cobwebby.  Flowers 
white,  yellow,  or  rose-color. 

1.  (Enothera  biennis,  L.     (L.,  bi,  twice;  annus,  year.)     COMMON  EVENING 
PRIMROSE.     Erect  and  mostly  stout  annuals  or  biennials,  i  to  5  feet  high,  more 
or  less  pubescent.     Leaves  lanceolate,  acute,  or  acuminate  at  the  apex,  narrowed 
toward  the  base,  sessile  or  short-petioled,  i  to  6  inches  long,  repand-denticulate. 
Flowers  opening  in  the  evening,  bright  yellow,  i  to  2  inches  broad.    Calyx  tube 
i  to  25  inches  long;  reflexed  lobes  of  the  calyx  cohering  at  their  tips. 

2.  (Enothera  speciosa,    Nutt.     (L.,  speciosus,  showy.)     SHOWY   PRIMROSE. 
Erect  or  more  or  less  decumbent  perennials,  from  6  inches  to  3  feet  high.     Leaves 
lanceolate  to  linear-lanceolate,  sessile  or  short-petioled,  repand-denticulate  or  sinuate- 
pinnatifid,  2  to  3  inches  long.     Flowers  usually  few,  13  to  3^  inches  broad,  white  to 
pale  pink.    Tube  of  the  calyx  rather  longer  than  the  ovary.     Capsule  strongly 
8-ribbed.     Plant  pubescent.     Prairies. 

3.  (Enothera  Missouriensis,  Sims.    MISSOURI  EVENING  PRIMROSE.    Decum- 
bent perennial  with  short,  silken  pubescence.     Leaves  rather  thick,  oval  to  linear 
or  oblong-lanceolate,  narrowing  to  a  slender  petiole,  2  to  6  inches  long,  remotely 
denticulate  or  entire.    Flowers  axillary,  yellow,  3  to  6  inches  broad,  very  striking. 
Calyx  tube  2  to  6  inches,  much  exceeding  the  ovary.     Capsules   very  broadly 
winged.     Crests  of  limestone  hills. 

UMBELLl'FER^.    PARSLEY  or  CARROT  FAMILY. 

Herbs,  mostly  with  hollow,  ribbed  stems  and  compound  or  decom- 
pound leaves  which  clasp  the  stem  at  the  base.  Flowers  small  in 
simple  or  compound  umbels ;  in  the  latter  case  the  ultimate  umbels  are 
called  umbellets ;  the  whorl  of  bracts  usually  subtending  the  general 
umbel  is  called  the  involucre,  while  that  subtending  the  umbellet  is 
termed  the  involucel.  Ovary  entirely  inferior,  2-celled  and  2-ovuled ; 
the  limb  of  the  calyx  surmounting  the  ovary  either  wanting  or  reduced 
to  a  mere  5-toothed  border.  Styles  2  and  filiform,  their  bases  frequently 
thickened,  forming  a  stylopodium.  Petals  and  stamens  5,  inserted  on  a 


Dicotyledones.  83 

disk  crowning  the  ovary.  Fruit  consisting  of  2  seedlike  carpels,  each 
of  which  bears  5  primary  ribs,  and  often  4  intermediate  ones.  Longi- 
tudinal oil  tubes  commonly  occur  in  the  tissue  of  the  carpels  between 
the  ribs ;  these  are  best  seen  in  cross  sections  of  the  carpels. 


I.  HERACLEUM.    Cow  Parsnip. 

(Named  for  Herakles,  Greek  form  of  Hercules.) 

Tall,  stout,  and  often  pubescent  perennials,  with  large,  ternately 
compound  leaves  and  broad,  compound  umbels  of  white  flowers. 
Involucre  of  the  general  umbel  deciduous  or 
none ;  bracts  of  the  involucels  numerous  and 
linear.  Calyx  teeth  obsolete  or  wanting. 
Petals  obcordate,  the  outer  commonly  larger 
and  2-cleft.  Stylopodium  or  disklike  expan- 
sion at  the  base  of  the  style  common  in  this 
family,  thick  and  conic.  Fruit  broadly  oval, 
obovate,  or  orbicular,  flattened  dorsally,  and 
broadly  winged  on  the  sides.  Ribs  filiform 
with  a  single  oil  tube  in  each  interval  between 
the  ribs  extending  only  halfway  down  the 
fruit,  as  seen  in  cross  sections. 


i.  Heracleum  lanatum,  Michx.  (L.,  lanatus, 
woolly.)  Cow  PARSNIP.  Stems  4  to  8  feet  high, 
stout,  ribbed,  and  woolly.  Leaflets  broad,  irregularly 
lobed  and  cut-toothed,  pubescent  beneath.  In  moist 
ground. 


FIG.  349. 

Diagrams  of  Carum  Carvi : 
i,  a  single  flower;  2,  lon- 
gitudinal diagram  of  a 
flower ;  3,  ripened  fruit ; 
4,  cross-section  of  a  fruit, 
showing  oil  ducts  in  black. 
—AFTER  WOSSIDLO.  . 


H.  PASTINACA.    Parsnip. 

(The  Latin  name,  from  pastus,  food.) 

Mostly  biennial,  tall,  branching,  and  glabrous  herbs.  Leaves  pin- 
nately  compound.  Flowers  yellow  in  compound  umbels;  involucre 
and  involucels  usually  wanting.  Calyx  teeth  obsolete.  Stylopodium 
depressed.  Fruit  flattened  dorsally,  winged  on  the  margins,  and  with 
filiform  ribs  on  the  back :  a  single  oil  tube  in  each  interval. 

i.  Pastinaca  sativa,  L.  (L.,  sativus,  that  is  sown  or  plan  ted.)  WILD  PARSNIP. 
Stems  2  to  5  feet  high  from  a  fleshy,  conic  root.  Lower  leaves  about  i|  feet  long, 
petioled,  pinnately  compound;  upper  leaves  much  smaller;  leaflets  cut-toothed. 
Roadsides  and  waste  places. 


84  Introduction  to  Botany. 


in.  PEUCEDANUM.    Parsley. 

(The  old  Greek  name.) 

Perennial  herbs,  nearly  or  quite  acaulescent,  from  thickened  roots. 
Leaves  mostly  bipinnate  or  finely  dissected.  Flowers  white  or  yellow 
in  compound  umbels.  General  involucre  wanting,  but  involucels  of 
several  bracts.  Calyx  teeth  mostly  obsolete.  Fruit  orbicular,  oval,  or 
oblong,  flattened  dorsally,  and  winged  on  the  margins.  Dorsal  and 
intermediate  ribs  filiform;  1-4  oil  tubes  in  the  intervals. 

i.  Peucedanum  foeniculaceum,  Nutt.  (L.,  fceniculum,  fennel.)  FENNEL- 
LEAVED  PARSLEY.  Peduncles  4  to  10  inches  high,  overtopping  the  leaves, 
tomentose  or  nearly  smooth.  Leaves  twice  or  thrice  pinnate,  the  segments  finely 
dissected,  the  petioles  sheathing  at  the  base.  Bractlets  of  the  involucels  united 
below,  tomentose.  Flowers  yellow.  Umbels  unequally  3~i2-rayed.  Fruit  broadly 
oval  and  glabrous,  with  thin  lateral  wings.  Prairies. 


IV.  SANICULA.    Sanicle  or  Black  Snakeroot. 

(From  low  Latin,  sanicula,  diminutive  of  sanus,  healthy.) 

Rather  tall,  glabrous,  perennial  herbs,  with  few  palmately  lobed 
or  parted  leaves,  the  basal  leaves  long-petioled ;  flowers  greenish  or 
yellowish  in  irregular  or  compound  umbels,  capitate  in  the  umbellets. 
Involucre  foliaceous ;  involucels  of  few  leaves.  Fruit  globular,  not 
ribbed,  and  thickly  covered  with  hooked  prickles,  each  with  5  oil 
tubes. 

1.  Sanicula  Marylandica,  L.     BLACK  SNAKEROOT  or  SANICLE.     Usually 
unbranched,  from  i|  to  4  feet  high.     Leaves  3~7-parted,  the  divisions  obovate  to 
oblanceolate,  irregularly  serrate  and  dentate.     Leaves  of  the  general  involucre 
3-cleft ;  involucel  leaves  few  and  small.     Umbels  2-4-rayed.     Flowers  both  perfect 
and  staminate,  the  staminate  in  separate  heads.     Petals  greenish  white,  scarcely 
exceeding  the  caJyx.     Fruit  ovoid  and  beset  with  stout  bristles ;  the  styles  recurved, 
longer  than  the  bristles.     In  rich  woods. 

2.  Sanicula  Canadensis,  L.    SHORT-STYLED  SNAKEROOT.     Staminate  flowers 
never  in  separate  heads,  and  styles  shorter  than  the  prickles  on  the  carpels.    Leaves 
3~5-divided,  petioled,  the  divisions  sharply  serrate.     In  dry  woodlands. 

3.  Sanicula  gregaria,  Bicknell.     (L..,gregarius,  belonging  to  a  herd  or  flock.) 
CLUSTERED  SNAKEROOT.    Stems  usually  clustered,  and  yellow  petals  much  sur- 
passing the  calyx,     i  to  3  feet  tall.     Leaves  5-divided,  the  divisions  lanceolate  to 
obovate-cuneate.     In  moist  woods  and  thickets. 


Dicotyledones.  85 


V.   CKEROPHYLLUM.     Chervil. 
(Gr.,  chafro,  to  gladden;  phyllon,  leaf.     From  agreeable  odor  of  the  leaves.) 

Annuals,  growing  mostly  in  moist  soil.  Leaves  ternately  decom- 
pound with  pinnatifid  leaflets.  Flowers  white,  few  in  the  umbellets ; 
umbels  few-rayed.  Involucre  usually  none ;  involucels  of  numerous 
small  bracts.  Calyx  teeth  obsolete ;  petals  reflexed  at  the  apex.  Car- 
pels more  or  less  5 -angled.  Fruit  oblong  to  linear-oblong.  Ribs 
slender  and  obtuse ;  oil  tubes  solitary  in  the  intervals. 

i.  Chaerophyllum  procumbens,  Crantz.  (L.,  procumbens,  falling  forward.) 
SPREADING  CHERVIL.  Stems  slender,  branched,  mostly  spreading,  more  or  less 
pubescent,  6  to  18  inches  high.  Umbels  2-6-rayed.  Flowers  few  in  the  umbellets. 
Fruit  linear-oblong  and  glabrous.  In  moist  ground. 

VI.  OSMORRHIZA.    Sweet  Cicely. 
(Gr.,  osme,  a  scent;  rhiza,  root.) 

Perennial  herbs  from  fleshy,  clustered,  aromatic  roots.  Leaves  ter- 
nately decompound.  Flowers  white  in  few-rayed  umbels.  Involucre 
and  involucels  wanting  or  of  few  bracts.  Calyx  teeth  obsolete ;  petals 
incurved  at  the  apex.  Fruit  oblong-linear,  short-beaked,  attenuate  at 
the  base,  usually  quite  bristly  along  the  equal  ribs.  Oil  tubes  obsolete 
or  none. 

1.  Osmorrhiza  brevistylis,   DC.      (L.,  brevis,  short;  stylus,  stem  or  point.) 
SHORT-STYLED  or  WOOLLY  SWEET  CICELY.     Erect,  rather  stout,  becoming 
branched  above,  i£  to  3  feet  high,  villous  pubescent.     Lower  leaves  large,  long- 
petioled,  sometimes  i  foot  across.     Umbellets  on   long  peduncles,  2-6-flowered. 
Style  and  stylopodium  about  ^  inch  long.     In  woods. 

2.  Osmorrhiza  longistylis,   DC.     (L.,  longus,  long;   stylus,  stem   or  point.) 
LONGER-STYLED  or  SMOOTHER  SWEET  CICELY.    Similar  to  the  preceding  species, 
but  only  slightly  pubescent  or  glabrous,  and  style  and  stylopodium  about  ^  inch 
long.    In  woods. 

VH.  ERIGENIA.    Harbinger  of  Spring.       ' 

(Gr.,  erigeneia,  born  in  the  spring.) 

Low,  glabrous,  nearly  acaulescent  plants  rising  from  a  deep  tuber. 
Leaves  ternately  decompound,  generally  only  i  or  2.  Flowers  white 
in  small  umbels.  Calyx  teeth  obsolete ;  petals  flat  and  entire.  Fruit 
nearly  orbicular,  incurved  at  top  and  bottom;  carpels  nearly  kidney- 
shaped,  each  5-ribbed,  and  1-3  small  oil  tubes  in  each  interval. 


86  Introduction  to   Botany. 

i.  Erigenia  bulbosa,  Nutt.  (L.,  bulbosus,  full  of  bulbs.)  HARBINGER  OF 
SPRING.  Stem  3  to  9  inches  high  with  a  leaf  subtending  the  general  umbel. 
Petioles  sheathing  at  the  base.  Pedicels  very  short  in  flower.  Fruit  about  j^  inch 
tall,  broader  than  tall. 

CORNACE^.     DOGWOOD  FAMILY. 

Shrubs  or  trees,  usually  with  entire  leaves.  Flowers  perfect,  polyga- 
mous, or  direcious,  in  cymes  or  heads.  Ovary  inferior.  Calyx  teeth 
4-5  or  wanting.  Petals  4-5,  sometimes  none,  inserted  at  the  base  of 
an  epigynous  disk.  Stamens  inserted  with  the  petals,  and  of  the  same 
number  or  more  numerous.  Ovary  i-2-celled  with  a  single  ovule  in 
each  cavity.  Style  i.  Fruit  a  i -2-celled,  i-2-seeded  drupe. 

I.   CORNUS.    Cornel  or  Dogwood. 

(L.,  cornu,  horn,  from  the  hardness  of  the  wood.) 

Shrubs  or  trees,  with  mostly  opposite  or  verticillate  leaves,  and  small 
white,  greenish,  or  purple  flowers  in  cymes  or  involucrate  heads.  Calyx 
4-toothed ;  petals  4 ;  stamens  4.  Ovary  2-celled  with  i  ovule  in  each 
cavity.  Stone  of  the  drupe  2-celled  and  2-seeded. 

1.  Cornus  florida,   L.     (L.,  fioridus,  flowery.)     FLOWERING  DOGWOOD.    A 
shrub  or  small  tree,  with  mostly  ovate  or  oval,  petioled  leaves.    Flowers  greenish 
yellow,  in  heads ;  bracts  of  the  involucre  i\  to  2$  inches  long,  white  or  pinkish, 
emarginate,  strongly  veined.     Fruit  ovoid  and  scarlet,  crowned  by  the  persistent 
calyx.     In  woods. 

2.  Cornus  circinata,  L'Her.     (L.,  circinatus,  rounded.)     ROUND-LEAVED  COR- 
NEL or  DOGWOOD.     Shrub,  3  to  10  feet  high.    Branches  greenish  and  warty. 
Leaves  orbicular  or  very  broadly  ovate,  woolly  beneath.     Flowers  in  flat  cymes ; 
fruit  blue.     In  shady  and  rocky  places. 

3.  Cornus  sericea,  L.     (L.,  sericeus,  silken.)     SILKY  CORNEL  or  KINNIKIN- 
NIK.    A  shrub,  3  to  10  feet  high,  with  purplish,  pubescent  twigs.     Leaves  narrowly 
ovate  or  elliptical,  downy  beneath.    Calyx  teeth  lanceolate.    Cymes  flat.     Fruit 
pale  blue.    Along  streams  and  in  damp  woods. 

4.  Cornus  asperif61ia,  Michx.     (L.,  asper,   rough;   folium,  leaf.)     ROUGH- 
LEAVED  CORNEL  or  DOGWOOD.     Shrub,  3  to  15  feet  high;  branches  brownish 
and  rough  pubescent.    Leaves  ovate  or  elliptic,  acuminate,  downy  beneath  and 
rough  pubescent  above.    Calyx  teeth  minute ;  fruit  white.     In  dry  soil  or  exposed 
hillsides. 

ERICACEJE.     HEATH  FAMILY. 

Shrubs  or  perennial  herbs.  Ovary  superior.  Calyx  and  corolla  more 
or  less  4~5-parted  or  cleft.  Stamens  usually  as  many  or  twice  as  many 
as  the  lobes  of  the  corolla.  Anthers  usually  opening  by  terminal 
chinks  or  pores.  Style  i  ;  ovary  3-io-celled. 


Dicotyledones.  87 

I.  EPIGAEA.    Ground  Laurel  or  Trailing  Arbutus. 
(Gr.,  epi)  upon;  ge,  the  earth.     From  the  trailing  habit.) 

Prostrate,  more  or  less  hairy,  branching  shrubs,  with  evergreen 
leaves.  Flowers  clustered  at  the  end  of  the  branches,  white  or  pink, 
fragrant.  Sepals  5,  oblong.  Corolla  salver-formed,  mostly  5-lobed. 
Stamens  10,  attached  to  the  base  of  the  corolla  and  about  as  long  as 
its  tube.  Ovary  ovoid,  hirsute.  Style  columnar;  stigma  5-lobed. 

i.  Epigaea  repens,  L.  (L.,  repens,  trailing.)  TRAILING  ARBUTUS.  MAY- 
FLOWER. GROUND  LAUREL.  Leaves  oval,  oblong-ovate,  or  nearly  orbicular, 
thick.  Branches  6  to  15  inches  long.  Flowers  appearing  very  early  in  the  spring, 
exhaling  a  spicy  fragrance.  In  sandy  woods  or  rocky  soil,  especially  under  ever- 
green trees. 

n.  GAYLUSSACIA.    Tangleberry  or  Huckleberry. 

(Named  for  Gay-Lussac,  chemist.) 

Shrubs,  with  alternate,  entire  leaves,  sometimes  serrated.  Flowers 
in  lateral,  bracted  racemes,  small  and  white  or  pink.  Corolla  tube  urn- 
shaped  or  campanulate,  with  5-lobed  limb.  Calyx  tube  short,  the  limb 
with  5  short  lobes  or  teeth.  Stamens  10,  included.  Anthers  tapering 
upward  and  opening  at  the  summit.  Ovary  lo-celled.  Fruit  a  berrylike 
drupe  with  10  seedlike  nutlets. 

1.  Gaylussacia  frondosa,  T.  &  G.    (L.,  frondosus,  leafy.)    BLUE  TANGLE  or 
TANGLEBERRY.     Erect  shrubs,  2  to  4  feet  high.     Leaves  obovate-oblong,  blunt, 
under  surface  pale  and  glaucous,  and  resinous.    Flowers  in  loose  racemes,  greenish 
pink,  round-campanulate.     Fruit  globose,  dark  blue,  with  a  bloom,  sweet  and 
edible.     In  moist  woods  and  thickets. 

2.  Gaylussacia  resinosa,  T.  &  G.    (L.,  resinosus,  full  of  resin  or  gum.)    BLACK 
or  HIGH-BUSH  HUCKLEBERRY.    Shrub,  i  to  3  feet  high.    Branches  numerous, 
erect  or  ascending,   and  rigid,   somewhat    pubescent.      Leaves  mostly  oval  or 
oblong-ovate,  when  young  thickly  covered  with  resinous  globules,  green  on  both 
sides.     Inflorescence  a   i-sided  raceme.     Bracts  shorter  than   the  pedicels  and 
deciduous.     Fruit  black,  without  bloom,  sweet.    Rocky  woods  and  thickets,  and 
in  swamps. 

m.  VACCINIUM.    Blueberry,  Bilberry,  Whortleberry,  or  Cranberry. 

(The  old  Latin  name.) 

Shrubs,  with  alternate  and  often  coriaceous  leaves.  Flowers  small, 
white,  pink,  or  red,  urn-shaped  or  campanulate,  in  terminal  or  lateral 
racemes,  or  sometimes  solitary.  Calyx  tube  globose  and  adnate  to  the 
ovary,  the  persistent  limb  4~5-toothed  or  lobed.  Stamens  8-10,  the 


88  Introduction  to   Botany. 

anthers  becoming  tubular  above,  sometimes  awned  on  the  back,  open- 
ing by  terminal  pores.  Ovary  4-5-celled,  or  8-io-celled  by  false 
partitions.  Fruit  a  many-seeded  berry. 

1.  Vaccinium  corymbosum,   L.     (Gr.,  korymbos,  a  cluster.)     HIGH-BUSH  or 
TALL   BLUEBERRY.     Shrub,  6  to  15  feet  high.    Leaves  mostly  oblong-ovate  or 
elliptical.     Flowers  tubular,  urn-shaped,  appearing  with  the  leaves,  in  short  racemes. 
Calyx  5-lobed;    corolla  5-toothed.     Stamens   10.     Berries  blue,  with  a  bloom, 
pleasantly  acid.     In  swamps  and  low  thickets. 

2.  Vaccinium  Canadense,  Richards.    CANADA  BLUEBERRY.    Low-branching 
shrub,  6  inches  to  2  feet  high.     Leaves  narrowly  oval  to  elliptic-lanceolate,  pubes- 
cent at  least  beneath.    Branches  downy.     Flowers  oblong-campanulate,  greenish 
white,  appearing  with  the  leaves.     Berries  mostly  blue,  with  a  bloom.     Swamps 
and  moist  woods. 

3.  Vaccinium  Pennsylvanicum,  Lam.    DWARF  or  LOW-BUSH  BLUEBERRY. 
Similar  in  general  aspect  to  the  preceding  species,  but  branches  and  leaves  nearly 
or  quite  glabrous,  the  branches  green  and  warty.     Corolla  white  or  pinkish,  slightly 
constricted  at  the  throat.    Berries  blue,  with  a  bloom,  sweet.     Dry  hills  or  dry,  sandy 
soil: 

PRIMULACEJE.     PRIMROSE  FAMILY. 

Herbs,  with  simple  leaves,  which  are  mostly  opposite  or  verticillate, 
but  sometimes  alternate.  Calyx,  with  rare  exceptions,  free  from  the 
ovary,  mostly  5 -parted.  Corolla  gamopetalous,  the  limb  usually  5-cleft 
or  lobed.  Stamens  as  many  as  the  lobes  of  the  corolla  and  opposite- 
them,  inserted  on  the  tube  of  the  corolla  or  at  its  base.  Ovary  i-celled, 
with  a  free  central  placenta  bearing  many  ovules. 

I.  PRIMULA.    Primrose  or  Cowslip. 

(Latin  diminutive  of  primus,  first,  alluding  to  early  flowering.) 

Perennial  herbs,  with  leaves  clustered  at  the  base,  and  flowers  often 
borne  in  umbels  at  the  end  of  a  scape.  Corolla  salver-shaped,  the  tube 
often  enlarging  above  the  insertion  of  the  stamens,  5-lobed,  the  lobes 
mostly  notched  or  obcordate.  The  five  stamens  not  exceeding  the  tube 
of  the  corolla.  Ovary  superior,  oblong,  ovoid,  or  globose  ;  style  filiform, 
and  stigma  capitate,  dehiscing  at  the  apex  into  5  valves  or  10  teeth. 

1.  Primula  Sinensis,  Sabine.     (Latinized  form,  relating  to  China.)     CHINESE 
PRIMROSE.     Cultivated  in   greenhouses,  etc.     Flowers   showy,  white,  purple,  or 
pink.     Lobes  of  the  corolla  sometimes  cut-fringed.     Plant  downy;  leaves  variously 
cut  or  crisped.    Calyx  inflated. 

2.  Primula  grandiflora,  Lam.     (L,.,grandis,  large;  flos^floris,  flower.)     TRUE 
PRIMROSE.     Cultivated  from  Europe.    .Sulphur- yellow  flowers  rising  on  slender 
pedicels  from  the  axils  of  basal  leaves,  no  proper  scape  being  developed.    Corolla 
flat.     Leaves  somewhat  hairy  on  their  under  sides. 


Dicotyledones.  89 


H.  ANDROSACE.    Starfoil. 

(Greek  name  of  a  polyp  supposed  to  be  a  plant.) 

Low  annual  or  sometimes  perennial  herbs,  with  small,  tufted  basal 
leaves,  and  small  white  or  pink  flowers  borne  in  scapose,  involucrate 
umbels.  Calyx  5-lobed  or  cleft,  persistent.  Corolla  salver-  or  funnel- 
shaped,  contracted  at  the  throat,  the  tube  shorter  than  the  calyx. 
Stamens  5,  included.  Ovary  globular  or  turbinate.  Capsule  5-valved. 

i.  Androsace  occidentalis,  Pursh.  (L.,  occidentalis,  western.)  WESTERN 
STARFOIL.  Small,  nearly  or  quite  glabrous  annual.  Scapes  i  to  3  inches  long, 
mostly  clustered,  erect  or  ascending  from  fibrous  roots.  The  basal  leaves  and 
leaves  of  the  involucre  oblong-ovate.  Corolla  white,  shorter  than  the  calyx. 
Pedicels  slender.  In  dry  soil. 

HI.  ANAGALLIS.    Pimpernel. 

(The  old  Greek  name,  possibly  from  ana,  again;  agallo,  to  delight  in.) 

Diffuse  or  erect  annual  or  perennial,  with  mostly  opposite  or  ver- 
ticillate  sessile  or  short-petioled  leaves,  and  white,  blue,  red,  or  pink 
flowers  on  axillary  peduncles.  Calyx  and  corolla  5-parted ;  corolla 
rotate,  longer  than  the  calyx.  Stamens  5,  inserted  at  the  base  of  the 
corolla,  more  or  less  pubescent,  distinct  or  united  into  a  ring  at  the 
base.  Ovary  globose  with  many  ovules.  Capsule  circumscissile. 

i.  Anagallis  arvensis,  L.  (L.,  arvensis,  belonging  to  the  fields.)  COMMON 
PIMPERNEL.  Usually  much  branched  annual.  Leaves  ovate  and  sessile,  shorter 
than  the  peduncles.  Slender  peduncles  recurved  in  fruit.  Lobes  of  the  corolla 
fringed  with  teeth  or  glands.  Flowers  scarlet,  sometimes  white,  opening  only  in 
bright  weather.  In  waste  places. 

IV.  CENTUNCULUS.    Chaffweed. 

(Derivation  uncertain.) 

Low,  glabrous  annuals,  with  small,  alternate,  and  entire  leaves  and 
minute,  solitary,  axillary  flowers.  Calyx  4-5 -parted;  corolla  4-5-cleft, 
with  urn-shaped  tube  and  spreading  lobes,  shorter  than  the  calyx. 
Stamens  4-5,  filaments  short,  inserted  on  the  throat  of  the  corolla. 
Capsule  globose,  containing  many  seeds,  circumscissile. 

i.  Centunculus  minimus,  L.  (L.,  minimus,  least.)  CHAFFWEED  or  FALSE 
PIMPERNEL,  i  to  6  inches  high.  Leaves  spatulate  or  obovate,  short-petioled. 
Flowers  minute,  pink,  nearly  sessile  in  the  axils  of  the  leaves,  mostly  4-parted. 
In  moist  soil. 


90  Introduction  to  Botany. 


V.  DODECATHEON.    American  Cowslip. 

(Gr.,  dodeka,  twelve;  theoi,  gods.     Pliny's  name  for  the  primrose,  supposed  to  be  under  the 
care  of  the  gods.) 

Glabrous  perennial  herbs,  with  entire  or  merely  repand  basal  leaves, 
and  flowers  in  involucrate  umbel  terminating  a  scape.  Calyx  5-parted 
with  lobes  at  first  reflexed.  Corolla  5-parted  with  reflexed  lobes,  the 
tube  short  and  thickened  at  the  throat.  Stamens  5,  monadelphous, 
connivent  into  a  cone,  inserted  on  the  throat  of  the  corolla.  Ovary 
ovoid  or  nearly  globose,  containing  numerous  ovules. 

i.  Dodecatheon  Meadia,  L.  AMERICAN  COWSLIP  or  SHOOTING  STAR.  Peren- 
nial, with  short  rootstock  and  fibrous  roots.  Leaves  mostly  oblanceolate,  narrow- 
ing into  a  petiole,  entire  or  sometimes  toothed.  Scape  8  inches  to  2  feet  high. 
Corolla  pink,  purple,  or  white.  Often  cultivated.  Rich  woods  and  prairies. 

EBENACE^.    EBONY  FAMILY. 

Trees  or  shrubs,  with  alternate,  exstipulate,  entire  leaves  and  polyga- 
mous, regular  flowers.  Calyx  3~7-lobed,  free  from  the  3-i2-celled 
ovary.  Corolla  gamopetalous,  3-7-lobed.  Stamens  inserted  on  the 
tube  of  the  corolla,  and  2  to  4  times  as  many  as  its  lobes.  Fruit  a 
berry  containing  I  or  more  seeds,  with  bony  testa. 

I.  DIOSPYROS.    Date  Plum  or  Persimmon. 

(Gr.,  dies,  of  Jove;  pyros,  grain.) 

Trees  or  shrubs,  with  simple  leaves  and  lateral,  solitary,  or  clustered, 
direciously  polygamous  flowers.  Corolla  urn-shaped,  4-6-lobed.  Calyx 
4-6-lobed.  Stamens  8-20  in  the  sterile  flowers,  fewer  and  imperfect,  or 
even  wanting,  in  the  pistillate  flowers.  Ovary  globose  or  ovoid  ;  styles 
2-6.  Berry  large  and  pulpy,  containing  4-12  hard  and  flat  seeds. 

i.  Diospyros  Virginiana,  L.  COMMON  PERSIMMON.  Tree,  with  hard  and 
dark  bark.  Leaves  thickish,  ovate-oblong  to  oval,  nearly  or  quite  glabrous.  Calyx 
4-parted.  Corolla  mostly  4-lobed,  greenish  yellow,  thickish,  campanulate,  or  some- 
what urn-shaped ;  sterile  flowers  smaller  than  the  fertile.  Fruit  very  astringent  when 
green,  becoming  reddish  yellow,  and  sweetening  after  exposure  to  frost.  Woods 
and  old  fields. 

OLE  ACE  JE.    OLIVE  FAMILY. 

Trees  or  shrubs,  with  mostly  opposite,  pinnate,  or  simple  exstipulate 
leaves,  and  flowers  in  panicles,  cymes,  or  fascicles.  Calyx  4-cleft  or 
obsolete ;  corolla  4-cleft,  or  4-petalous,  or  sometimes  wanting.  Stamens 


Dicotyledones.  91 

2-4,  mostly  2,  inserted  on  the  corolla.  Ovary  superior,  2-celled,  and 
with  2,  or  at  most  a  few,  ovules  in  each  cavity.  Fruit  a  berry,  drupe, 
samara,  or  capsule. 

I.  SYRINGA.    Lilac. 

(Gr.,  syrinx,  a  pipe,  possibly  relating  to  the  narrow  tube  of  the  corolla.) 

Shrubs,  with  simple,  entire,  opposite  leaves  and  dense  panicles  of 
gamopetalous  flowers.  Calyx  mostly  4-toothed.  Corolla  salver-formed 
with  a  4-lobed  limb.  Stamens  2,  inserted  near  the  summit  of  the  corolla 
tube.  Ovary  2-celled  with  2  ovules  in  each  cell.  Style  elongate ;  stigma 
2-cleft.  Fruit  a  narrowly  oblong  capsule.  Natives  of  the  Old  World, 
cultivated  for  ornament. 

1.  Syringa  vulgaris,  L.     (L,.,  vulgaris,  common.)    COMMON  LILAC.   A  shrub, 
common  in  gardens.     Leaves  ovate,  somewhat  cordate  at  base,  acuminate  at  the 
apex,  green  and  smooth  on  both  sides.     Flowers  lilac  or  pale  violet,  in  compact, 
terminal  panicles  or  thyrses  appearing  soon  after  the  leaves,  fragrant.    A  white 
variety  also  occurs. 

2.  Syringa  Persica,  L.    PERSIAN  LILAC.     Base  of  leaves  narrower  and  some- 
what tapering ;  leaves  nearly  lance-ovate. 

H.  FRAXINUS.    Ash. 

(The  classical  Latin  name.) 

Trees,  with  opposite,  odd-pinnate  leaves  and  polygamous  or  dioecious 
flowers  in  dense  panicles  or  racemes  in  the  axils  of  last  year's  leaves. 
Calyx  small,  4-cleft,  or  toothed,  or  entire,  sometimes  wanting.  Petals 
2-4,  or  wanting.  Stamens  usually  2,  sometimes  3-4.  Fruit  a  flat 
samara,  winged  all  around  or  only  at  the  apex. 

1.  Fraxinus  Americana,  L.    WHITE  ASH.    A  tall  tree.    Leaflets  5-9,  mostly  7, 
petioled,  commonly  ovate  to  ovate-lanceolate,  entire  or  denticulate,  dark  green  above 
and  paler  or  sometimes  pubescent  beneath.    Flowers  dioecious,  rarely  monoecious. 
Fruit  nearly  cylindrical,  about  half  as  long  as  the  wing,  which  springs  from  its 
summit.     In  rich  woods. 

2.  Fraxinus  quadrangulata,  Michx.     (L.,  quadrus,  square ;  angulatus,  angled.) 
BLUE  ASH.     A  large  tree,  with  angular  twigs  and  7-11  chiefly  lanceolate  leaflets, 
which  are  short-stalked,  green  on  both  sides,  and  denticulate  or  finely  serrate. 
Flowers  dioecious.     Fruit  narrowly  oblong,  winged  on  the  sides  as  well  as  apex ; 
wing  often  notched.     In  woods. 

ASCLEPIADACE^aL.    MILKWEED  FAMILY. 

Perennial  herbs  or  shrubs,  usually  exuding  latex  or  milk  when 
wounded.  Flowers  perfect  and  mostly  in  umbels.  Ovary  of  2  carpels, 
which  are  united  only  at  the  summit  with  a  fleshy,  stigmatic  disk. 


92  Introduction  to   Botany. 

Numerous  ovules  on  a  parietal  placenta  in  each  carpel.  Anthers  more 
or  less  coherent  and  forming  a  closed  tube  around  the  carpels.  Pollen 
coherent  in  rather  horny  masses,  called  pollinia,  the  adjacent  pollinia  of 
contiguous  anthers  being  joined  together  by  an  inverted  V-shaped,  horny 
excretion  from  the  stigmatic  disk  (see  Fig.  108).  Nectar  receptacles 
occurring  as  a  5-lobed  or  parted  crown  or  corona. 

I.  ASCLEPIAS.    Milkweed  or  Silkweed. 

(Gr.,  asklepios,  god  of  medicine.) 

Herbs,  usually  with  opposite  or  verticillate  leaves.  Each  nectar 
receptaele  bearing  an  incurved  horn  within.  Calyx  usually  small,  divided 
into  5  segments ;  the  5  corolla  segments  reflexed  when  open.  Anthers 
tipped  with  a  scale  and  winged  along  the  sides.  Seeds  hairy-tufted  in 
all  but  i  species  (see  Fig.  129). 

1.  Asclepias  tuberosa,  L.     (L.,  tuberosus,  full  of  humps  or  lumps.)     BUTTER- 
FLY WEED  or  PLEURISY  ROOT.    Stems  erect  or  ascending,  hirsute-pubescent, 
milky   secretions   not   exuding   when  the   stems   are   broken.      Leaves   alternate, 
lanceolate-oblong.     Flowers  orange-colored  in  terminal  cymose  umbels.     In  dry 
fields. 

2.  Asclepias  deciimbens,  L.     (L.,  decumbens,  falling  down.)     DECUMBENT 
BUTTERFLY  WEED.     Somewhat  similar  to  the  preceding  species.    Leaves  elliptic 
to  oblong.     Stems  at  first  decumbent,  but  erect  nearer  the  apex.     In  dry  fields. 

3.  Asclepias  Cornuti,  Decaisne.     (L.,  cornutus,  horned.)     COMMON  MILK- 
WEED or  SILKWEED.    Stems  erect  and  stout,  3  to  5  feet  high,  finely  pubescent. 
Leaves  oval-oblong,  pubescent  beneath.     Flowers   greenish   white   with   purplish 
tinge,  in  dense  umbels.     Nectar  receptacles  exceeding  the  anthers,  and  incurved 
horns.      Follicles  3  to   5   inches  long,   tomentose   and   beset  with  soft  spinose 
processes.     In  rich  -ground. 

II.  ASCLEPIODORA. 

(Gr.,  asklepios,  god  of  medicine;  doron,  gift.) 

Similar  to  Asclepias.  but  without  horns  from  the  nectar  receptacles, 
and  with  corolla  lobes  ascending  or  spreading. 

i.  Asclepiodora  viridis,  Gray.  (L.,  viridis,  green.)  GREEN  MILKWEED. 
Stems  about  i  foot  high,  nearly  or  quite  glabrous.  Leaves  ovate-oblong  to  lanceo- 
late, short  petioled,  alternate.  Flowers  green  with  a  purplish  crown.  In  dry  soil. 

CONVOLVULACE^.     MORNING  GLORY  FAMILY. 

Mostly  twining  or  trailing  herbs,  sometimes  with  milky  secretions. 
Leaves  alternate.  Flowers  axillary,  solitary,  or  cymose,  regular  and 
perfect.  Calyx  5-parted  or  divided.  Corolla  gamopetalous,  generally 


Dicotyledones.  93 

with  an  elongated  tube,  the  limb  5 -angled,  lobed,  or  entire.  Stamens  5, 
alternate  with  the  lobes  of  the  corolla,  inserted  low  down  in  the  tube. 
Ovary  superior,  2-3-celled,  with  2  erect  ovules  in  each  cavity ;  or  some- 
times false  partitions  seem  to  double  the  number  of  cavities,  with 
apparently  I  ovule  in  each  cell.  Fruit,  a  globular  2-4-valved  capsule. 

I.  IPOMOEA.    Morning  Glory. 

(Ips,  a  worm;  homoios,  like.) 

Mostly  twining  or  trailing  annuals  or  perennials,  with  showy,  axillary, 
solitary,  or  cymose  flowers.  Sepals  5,  sometimes  unequal.  Corolla 
salver-shaped  to  funnel-form,  or  sometimes  nearly  campanulate,  ^-angled 
or  lobed.  Style  simple,  terminated  by  i-3-capitate  or  globose  stigmas. 
Stamens  and  style  often  included.  Capsule  globular,  4-6-seeded  and 
2-4-valved. 

1.  Ipomoea  pandurata,  Meyer.     (L., pandura,  a  sort  of  fiddle.)     WILD  POTATO 
VINE  or  MAN-OF-THE-EARTH.    Nearly  smooth  perennial,  trailing,  barely  climbing, 
from  a  massive  root.     Leaves  broadly  cordate,  or  sometimes  angular,  3-lobed  or 
fiddle-shaped.     Peduncles  i-5-flowered,  elongating  in  fruit.     Sepals  oblong,  obtuse, 
or  acute.     Corolla  funnel-form,  2  to  3  inches  long,  white  with  purple  stripes  in  the 
throat;  limb  5-lobed.     In  dry  soil. 

2.  Ipomoea  leptophylla,  Torr.     (Gr.,  leptos,  thin ;  phyllon,  leaf.)     BUSH  MORN- 
ING GLORY.     Smooth  perennial,  with  erect,  ascending,  or  reclining  stem,  2  to  4 
feet  long  from  an  enormous  root.     Much  branched.    Leaves  2  to  5  inches  long, 
linear,  acute  at  the  apex,  on  short  petioles.     Peduncles  i-4-flowered,  nearly  erect, 
shorter  than  the  leaves.    Sepals  broadly  ovate.    Corolla  about  3  inches  long,  funnel- 
form,  scarcely-lobed,  pink  or  purple.    Capsule  ovoid,  2-celled,  nearly  i  inch  long. 
In  dry  soil  of  western  plains. 

H.  CONVOLVULUS.    Bindweed. 

(L.,  convolvere,  to  twine.) 

Mostly  perennials,  with  twining,  trailing,  or  erect  stems  from  slender 
rootstocks.  Leaves  mostly  cordate  or  sagittate.  Calyx  sometimes  with 
a  pair  of  bracts  at  its  base.  Corolla  funnel-form  to  campanulate,  soli- 
tary or  clustered  in  the  axils  of  the  leaves,  white,  purple,  or  pink.  Sta- 
mens included  in  the  tube  of  the  corolla.  Style  slender ;  stigmas  "2, 
linear,  awl-shaped,  or  ovoid.  Ovary  i -2-celled  and  4-ovuled. 

i.  Convolvulus  sepium,  L.  (Gr.,  sepion,  bone  of  cuttle-fish.)  HEDGE  or  GREAT 
BINDWEED.  Stems  3  to  10  feet  long,  trailing  or  twining.  Leaves  triangular- 
hastate  on  slender  petioles.  Flowers  funnel-form  on  slender  peduncles,  white  or 
tinged  with  pink.  Two  large  bracts  at  the  base  of  the  calyx.  Stigmas  oblong.  In 
fields  and  waste  places,  preferring  moist  soil. 


94  Introduction  to   Botany. 

2.  Convolvulus  repens,  L.     (L.,  repens,  trailing.)      TRAILING  BINDWEED. 
I  to  3  feet  long,  trailing  or  twining,  pubescent  or  tomentose.     Leaves  sagittate  with 
basal  lobes  obtuse  or  rounded,  sometimes  cordate.    Peduncles  i -flowered.    Flowers 
white.     Stigmas  oblong.     Calyx  2-bracted.     In  dry  fields. 

3.  Convolvulus  spithamaeus,  L.    UPRIGHT  BINDWEED.    Erect  or  ascending, 
6  to  12  inches  high,  somewhat  pubescent.     Leaves  mostly  oblong-oval  and  short- 
petioled.     Flowers  white,  solitary  on  long  peduncles.     Calyx  subtended  by  2  large 
oval  bracts.    Stigmas  thick,  oblong.     In  dry,  sandy,  or  rocky  soil. 

4.  Convolvulus  arvensis,  L.     (L.,  arvensis,  belonging  to  the  fields.)     SMALL 
BINDWEED.    Stems  slender,  trailing  or  decumbent,  i  to  2^  feet  long,  nearly  or 
quite  glabrous.     Leaves  sagittate  at  the  base  and  somewhat  acute  at  the  apex. 
Peduncles   i-4-flowered,  but  commonly  2-flowered.     Corolla  short-funnel-form, 
white  or  pink.     Peduncles,  and  usually  the  pedicels,  bracted.     Calyx  not  bracted. 
Stigmas  linear.     In  fields  and  waste  places. 

POLEMONIACE^.     PHLOX  FAMILY. 

Herbs.  Flowers  in  corymbose  or  paniculate  clusters,  perfect  and 
mostly  regular.  Calyx  5 -cleft,  tubular  or  campanulate.  Corolla  5-lobed, 
tubular,  campanulate,  or  rotate.  Stamens  5,  inserted  on  the  tube  of  the 
corolla  and  alternate  with  its  lobes.  Ovary  superior,  3-celled ;  style 
3-lobed.  Capsule  few-  to  many-seeded,  3-valved. 

I.  PHLOX. 

(Gr., phlox,  flame,  an  ancient  name  for  Lychnis.) 

Perennial  or  annual  herbs,  with  opposite,  entire  leaves,  and  flowers 
borne  in  cymose,  mostly  bracted,  clusters.  Calyx  tubular  or  tubular- 
campanulate,  becoming  distended  and  rupturing  by  the  ripening  capsule. 
Corolla  salver-form  with  broad,  spreading  lobes.  Stamens  included, 
inserted  at  different  heights  on  the  corolla  tube.  Ovules  1-4  in  each 
of  the  3  cavities  x>f  the  ovary. 

1.  Phlox  maculata,  L.     (L.,  maculatus,  stained  or  spotted.)     WILD  SWEET 
WILLIAM.     Stems   erect,  i£  to   5  feet  high.    Sometimes  puberulent,  and  often 
flecked  with  purple.     Leaves,  excepting  the  uppermost,  opposite,  ovate  to  ovate- 
lanceolate,  2  to  5  inches  long.     Flowers  short-pediceled,  borne  in  elongated,  leafy 
panicles.     Calyx  teeth  lanceolate.     Flowers  mostly  pink  or  purple. 

2.  Phlox  glaberrima,  L.     (L.,glaberrimus,very  smooth.)     SMOOTH  PHLOX. 
Stems  i  to  3  feet  high,  smooth  and  slender.     Leaves  linear-lanceolate,  or  linear 
below,  15  to  4  inches  long.     Flowers  in  cymes  grouped  in  a  corymbose  cluster. 
Calyx  teeth    lanceolate-awl-shaped.      Corolla   mostly  pink,   with    obovate    lobes 
longer  than  the  tube.     Prairies  and  open  woods. 

3.  Phlox  pildsa,  L.     (L.,  pilosus,  downy.)     DOWNY  PHLOX.     Stems  slender, 
i  to  2  feet  high.     Plant  downy  or  hairy,  sometimes  glandular.     Leaves  i  to  4  inches 


Dicotyledones.  95 

long,  lanceolate  or  linear.  Flowers  in  corymbose-cymes.  Calyx  teeth  awl-shaped. 
Corolla  pink,  purple,  or  white  with  obovate  lobes  and  somewhat  pubescent  tubes. 
In  dry  soil. 

4.  Phlox  divaricata,  L.     (L.,  divaricatus,  spread  out  or  apart.)     WILD  BLUE 
PHLOX.    Stems  decumbent  at  the  base,  spreading,  viscid-pubescent,  9  to  18  inches 
high.    Leaves  lanceolate  to  ovate-lanceolate,  about   i£  inches  long,    Flowers  in 
loosely-flowered  cymules,  blue  or  lilac,  slightly  fragrant.    Calyx  teeth  awl-shaped. 
Lobes  of  the  corolla  obcordate,  emarginate,  or  entire,  slightly  longer  than  the  tube. 
In  damp  woods. 

5.  Phlox  subulata,  L.     (L.,su&ula,  an  awl.)     GROUND  or  Moss  PINK.    Stems 
diffuse,  matted,  branches  2  to  6  inches  long.    Leaves  mostly  linear-awl-shaped  or 
linear-lanceolate,  from  J  to  nearly  i  inch  long,  ciliate,  often  fascicled  at  the  nodes 
and  widely  spreading.     Calyx  teeth  somewhat  awl-shaped.    Corolla  pink,  purple, 
or  white,  its  lobes  shorter  than  the  tube.     On  rocky  or  sandy  hills  or  banks. 

HYDROPHYLLACEJE.     WATERLEAF  FAMILY. 

Herbs,  with  leaves  mostly  alternate.  Corolla  gamopetalous,  5-lobed 
or  parted,  salver-form  to  campanulate  or  rotate.  Calyx  5-cleft  or 
divided.  Stamens  5,  inserted  on  the  tube  of  the  corolla  or  at  its  base, 
alternate  with  its  lobes.  Ovary  superior,  i -celled  with  2  parietal  pla- 
centas, or  2-celled  by  the  ingrowth  and  coalescence  of  the  placentae. 
Styles  2,  sometimes  partly  united.  Fruit,  a  2-valved,  4-many-seeded 
capsule.  Flowers  in  cymes,  racemes,  or  spikes,  sometimes  solitary. 

I.  HYDROPHYLLUM.    Waterleaf. 

(Gr.,  hydor,  water;  phyllon,  leaf,  application  not  evident.) 

Perennial  or  biennial  herbs.  Leaves  lobed  or  pinnately  divided 
or  parted.  Flowers  white,  blue,  or  purple,  in  cymes.  Calyx  deeply 
5 -parted,  the  divisions  lanceolate  or  awl-shaped.  Corolla  campanulate, 
5-cleft,  with  a  linear,  grooved  appendage  extending  down  the  tube 
opposite  each  lobe.  Stamens  5,  exserted.  Filaments  bearded.  Ovary 
i -celled,  the  fleshy  placentae  nearly  filling  the  cavity,  each  bearing  2 
ovules.  Capsule  i-4-seeded. 

1.  Hydrophyllum  Virginicum,  L.    VIRGINIA  WATERLEAF.    Perennial  from 
scaly  rootstock.     Nearly  or  quite  glabrous.     Stem  slender,  ascending  or  erect,  i  to 
3  feet  long.    Leaves  with  5-7  ovate-lanceolate  or  oblong,  pointed,  pinnate  divisions, 
the  divisions  cut-toothed.     Peduncles  longer  than  the  petioles  of  the  upper  leaves. 
Calyx  lobes  narrowly  linear,  ciliate,  the  sinuses  not  appendaged.     Flowers  about  i£ 
inch  long,  purplish  or  white.     In  woods. 

2.  Hydrophyllum  Canadense,  L.    BROAD-LEAVED  WATERLEAF.    Perennial 
from  a  scaly  rootstock.    Stems  slender,  nearly  or  quite  glabrous,  i  to  2£  feet  high. 


96  Introduction  to   Botany. 

Leaves  rounded,  cordate  at  the  base,  palmately  5-y-lobed,  the  lobes  pointed  and 
unequally  toothed,  somewhat  pubescent.  Lower  leaves  long-petioled  and  very 
broad,  sometimes  nearly  i  foot  in  diameter;  upper  leaves  smaller  and  shorter- 
petioled.  Flowers  in  cymes,  purplish  or  white.  Calyx  lobes  linear-awl-shaped, 
smoothish,  sometimes  with  minute  appendages  in  the  sinuses.  Corolla  short- 
campanulate.  In  woods. 

3.  Hydrophyllum  appendiculatum,  Michx.  (L.,  appendicula,  a  small  appen- 
dage.) APPENDAGED  WATERLEAF.  Rough  and  hairy  biennial.  Stems  slender, 
i  to  2  feet  long.  Lower  leaves  long-petioled  and  pinnately  incised  or  divided,  the 
lobes  dentate  or  incised.  Upper  leaves  smaller,  rounded,  palmately  5-lobed,  the 
lobes  pointed  and  irregularly  toothed.  Calyx  with  a  reflexed  appendage  in  each 
sinus.  In  damp  woods. 

II.  ELLI'SIA. 
(Named  for  John  Ellis,  naturalist.) 

Slender  branching  annuals,  with  pinnately  lobed  or  divided  leaves 
and  small  white  or  bluish  flowers,  solitary  or  racemed.  Calyx  spread- 
ing, 5-lobed  or  parted,  enlarging  in  fruit.  Corolla  campanulate  or 
cylindric,  hardly,  or  not  at  all,  exceeding  the  calyx ;  5  minute  appen- 
dages within  the  tube.  Stamens  included.  Ovary  i -celled;  placentae 
as  in  Hydrophyllum,  each  2-4-ovuled. 

i.  Ellisia  Nyctelea,  L.  (Gr.,  nyktelios,  nightly.)  Somewhat  hairy,  6  to  12 
inches  high.  Leaves  ovate-oblong  in  outline,  the  lobes  mostly  oblong  and  cut- 
toothed.  Corolla  whitish.  Peduncles  opposite  the  leaves,  i-flowered.  In  shady 
and  damp  situations. 

BORAGINACE^.     BORAGE  FAMILY. 

Mostly  rough,  hairy  herbs,  but  sometimes  shrubs  and  trees,  with 
alternate,  entire  leaves  and  perfect  flowers  borne  in  cymes,  racemes, 
or  spikes,  which  are  often  scorpioid.  Calyx  5-lobed,  cleft,  or  parted. 
Corolla  gamopetalous,  mostly  5-lobed.  Stamens  5,  inserted  on  the 
tube  of  the  corolla  and  alternate  with  its  lobes.  Ovary  superior,  mostly 
deeply  4-lobed.  Style  undivided  or  2-cleft.  Fruit  appearing  like  4 
i -seeded  nutlets. 

I.  CYNOGLOSSUM.    Hound's  Tongue. 
(Gr.,  kyon,  dog;  glossa,  tongue.) 

Coarse  herbs,  with  long-petioled  basal  leaves  and  mostly  sessile 
upper  leaves.  Flowers  in  panicled,  somewhat  scorpioid  racemes.  Calyx 
5-parted.  Corolla  funnel-form,  its  tube  about  equaling  the  calyx,  and 
the  throat  closed  by  obtuse  scales  opposite  the  lobes.  Stamens 
included.  Nutlets  beset  with  short,  barbed  prickles. 


Dicotyledones.  97 

i.  Cynoglossum  officinale,  L.  (L.,  officina,  a  workshop.)  COMMON  HOUND'S 
TONGUE.  15  to  3  feet  high.  Soft,  hairy  biennial.  Upper  leaves  lanceolate  and 
sessile ;  lower  leaves  broadly  lanceolate,  tapering  into  a  long  petiole.  Flowers  in 
simple  or  branched  racemes,  which  elongate  in  fruit.  Calyx  lobes  ovate-lanceolate. 
Corolla  reddish  purple,  sometimes  white,  about  £  inch  in  diameter.  Nutlets 
flattened  on  their  upper  face.  In  pastures  and  waste  places. 


II.  LITHOSPERMUM.    Gromwell  or  Puccoon. 
(Gr.,  lithos,  stone;  sperma,  seed,  from  the  hardness  of  the  seeds.) 

Hairy  or  rough  annual,  biennial,  or  perennial,  with  alternate,  entire, 
sessile  leaves.  Roots  thick  and  often  reddish.  Flowers  in  leafy-bracted 
racemes  or  spikes,  or  solitary.  Calyx  5-cleft  or  parted,  with  narrow 
lobes.  Corolla  salver-form  or  funnel-form,  sometimes  crested  or  pubes- 
cent in  the  throat.  Stamens  5,  included,  inserted  on  the  tube  of  the 
corolla  and  alternate  with  its  lobes.  Nutlets  4  or  less,  white  and 
shining  or  brown  and  wrinkled. 

1.  Lithospermum  canescens,  Lehm.    (L.,  canescens,  becoming  hoary.)    HOARY 
PUCCOON.    Perennial,  pubescent,  and  somewhat  hoary,  6  to  18  inches  high.    Leaves 
oblong  or  ovate-oblong,  blunt,  downy  beneath  and  roughish  above.     Flowers  in 
short,  leafy  racemes.      Segments   of  the  calyx  linear-lanceolate,  shorter  than  the 
tube  of  the  corolla.     Corolla  orange-yellow  with  rounded,  entire  lobes,  crested  in 
the  throat.    Nutlets  white,  smooth,  and  shining.    On  prairies  or  in  open  woods. 

2.  Lithospermum  angustifolium,  Michx.    (L.,  angustus,  narrow ;  folium,  leaf.) 
NARROW-LEAVED  PUCCOON.     Pubescent  and  rough  perennial  from  a  deep  root, 
6  to  18  inches  high.     Leaves  linear  and  acute.     Flowers  in  terminal,  leafy  racemes. 
The  early  flowers  more  showy  and  with  longer  tubes  than  the  later.    Corolla  of  the 
early  flowers  about  i  inch  long,  bright  yellow,  the  tube  much  longer  than  the  seg- 
ments of  the  calyx,  the  lobes  erose-denticulate,  and  the  throat  crested.     Pedicels 
of  the  later,  cleistogamous  flowers  recurved  in  fruit.     Nutlets  white  and  shining, 
often  punctate.     On  prairies  or  in  dry  soil. 

3.  Lithospermum  arvense,  L.     (L.,  arvum,  a  plowed  field.)     CORN  GROM- 
WELL.    Rough,  somewhat  hoary.     Leaves  lanceolate  to  linear.     Flowers  whitish ; 
corolla  scarcely  longer  than  the  calyx ;  throat  naked.     In  waste  soil. 

III.  ONOSMODIUM.    False  Gromwell. 

(Named  from  resemblance  to  genus  Onosma.) 

Stout-bristly  or  rough-pubescent  perennial  herb,  with  alternate,  entire, 
prominently  veined  leaves  and  white,  greenish,  or  yellowish  flowers  in 
leafy-bracted  scorpioid  racemes  or  spikes.  Calyx  with  5  narrow  seg- 
ments. Corolla  tubular  or  tubular-funnel-form  with  5  erect  lobes. 


98  Introduction  to   Botany. 

Stamens  5,  included,  inserted  on  the  tube  of  the  corolla.  Style  filiform, 
long-exserted.  Ovary  4-parted,  but  producing  only  1-2  white,  shining 
nutlets. 

1.  Onosmodium  Carolinianum,  DC.    SHAGGY  FALSE  CROMWELL,    i  to  3 
feet  high,  beset  with  rough,  spreading  hairs.     Leaves  lanceolate  or  ovate-lanceo- 
late, acute.    Corolla  pubescent  outside,  yellowish  white.     On  prairies  or  in  dry 
fields. 

2.  Onosmodium  mdlle,  Michx.    (L.,  mollis,  soft.)    SOFT-HAIRY  FALSE  GROM- 
WELL.     i  to  2  feet  high,  pale,  clothed  with  short,  soft  hairs.     Leaves  ovate-lanceo- 
late, acute.    On  prairies. 

3.  Onosmodium  Virginianum,  DC.     VIRGINIA  FALSE  GROMWELL.    i  to  2 
feet  high.    Clothed  with  short,  appressed,  bristly  hairs.     Leaves  oblong  to  oblong- 
lanceolate,  blunt,  oblanceolate  below,  narrowing  to  a  petiole.    Corolla  yellowish 
white.     On  hillsides  or  banks  or  in  dry  thickets. 

VERBENACE^E.    VERVAIN  FAMILY. 

Herbs  or  shrubs,  with  mostly  opposite  or  verticillate  leaves.  Flowers 
somewhat  2-lipped,  or  regular,  in  spikes,  racemes,  cymes,  or  panicles. 
Calyx  4-5-lobed  or  cleft.  Corolla  mostly  with  cylindric  tube  and  2- 
lipped  or  4~5-lobed  and  regular.  Stamens  4,  didynamous,  or  as  many 
as  the  lobes  of  the  corolla,  sometimes  only  2,  inserted  on  the  tube  of 
the  corolla.  Ovary  superior,  mostly  2-4-celled,  but  not  4-lobed.  Style 
simple  ;  stigmas  1-2.  Fruit  separating  at  maturity  into  2-4  nutlets. 

I.  VERBENA. 

(Latin  name  for  any  sacred  herb.) 

Herbs,  with  opposite  leaves  and  flowers  in  terminal,  simple,  or  pani- 
cled  spikes.  Calyx  tubular,  5 -angled,  or  toothed.  Corolla  salver-form 
or  funnel-form,  with  spreading,  5-lobed  limb.  Stamens  4,  didynamous, 
or  rarely  2,  included.  Ovary  4-celled  with  i  ovule  in  each  cavity. 
Fruit  splitting  into  4  nutlets. 

1.  Verbena  Aubletia,  L.     LARGE-FLOWERED  VERBENA.     Perennial,  i  foot 
high  or  less,  soft  pubescent  or  smoothish.     Leaves  ovate  to  ovate-oblong  in  out- 
line, incisely  lobed  or  toothed,  or  3-cleft,  the  lobes  dentate.     Inflorescence  capitate, 
but  becoming  spicate.    Bracts  of  the  inflorescence  shorter  than,  or  hardly  equaling, 
the  calyx.     Calyx  teeth  slender,  awl-shaped.    Corolla  reddish  purple  or  lilac,  rarely 
white,  about  i  inch  long,  and  the  limb  £  inch  or  more  in  diameter.    On  prairies  or 
in  open  woods. 

2.  Verbena  bipinnatffida,  Nutt.     (L.,  bi,  twice;  pinnatus,  feathered;  findere,  to 
cut.)     SMALL-FLOWERED  VERBENA.     Perennials,  producing  suckers,  erect,  6  to 


Dicotyledones.  99 

18  inches  high.  Leaves  i-2-pinnatifid  into  oblong  or  linear  divisions.  Spikes 
solitary  at  the  ends  of  the  branches.  Bracts  of  the  inflorescence  mostly  exceeding 
the  calyx.  Corolla  bluish  purple  or  lilac,  limb  of  the  corolla  less  than  5  inch  broad. 
On  open  prairies. 

3.  Verbena  bractedsa,  Michx.  (L.,  bractea,  a  thin  plate.)  LARGE-BRACTED 
VERVAIN.  Perennial.  Stems  4-sided ;  much  branched  from  the  base,  the  branches 
decumbent  or  ascending,  6  to  15  inches  long.  Leaves  wedge-lanceolate  in  outline, 
short-petioled,  cut-pin natifid,  or  3-cleft.  Spikes  dense,  becoming  4  to  6  inches  long, 
with  conspicuous  bracts  longer  than  the  purple  flowers.  Corolla  about  |  inch  long. 
On  prairies  and  in  waste  places. 

LABlATJE.    MINT  FAMILY. 

Aromatic  herbs  or  shrubs,  with  opposite  leaves  and  usually  4-sided 
stems.  Flowers  chiefly  in  cymose  clusters,  which  are  often  aggregated 
into  spikes  or  racemes.  Calyx  mostly  5-toothed  or  lobed,  persistent. 
Corolla  gamopetalous,  mostly  2-lipped,  the  limb  4~5-lobed.  Stamens 
mostly  4  and  didynamous,  inserted  on  the  tube  of  the  corolla,  some- 
times only  2.  Ovary  superior  and  deeply  4-lobed,  with  I  ovule  in  each 
lobe.  Fruit,  4  seedlike  nutlets  at  the  bottom  of  the  persistent  calyx. 

I.  SCUTELLARIA.     Skullcap. 

(L.,  scutella,  a  dish,  alluding  to  calyx  in  fruit.) 

Bitter  annual  or  perennial  herbs.  Flowers  in  spikelike  racemes,  blue 
or  violet.  Calyx  2-lipped,  the  upper  lip  with  a  prominent  protuberance. 
Corolla  2-lipped,  its  tube  long,  ascending,  and  somewhat  curved,  dilated 
in  the  throat;  the  upper  lip  arched  and  the  lower  spreading  or  bent 
downward.  Stamens  4,  all  anther-bearing,  didynamous,  the  lower 
anthers  but  i -celled.  Ovary  4-parted ;  style  unequally  2-cleft.  Lips 
of  the*  calyx  closed  in  fruit. 

1.  Scutellaria  serrata,  Andrews.     (L.,  serratus,  notched  like  a  saw.)     SHOWY 
SKULLCAP.    Slender  perennial,  i  to  2  feet  high,  nearly  glabrous.     Leaves  ovate  to 
ovate-oblong,  coarsely  serrate  or  dentate.     Flowers   in   terminal    loose  racemes. 
Corolla  blue,  about  i  inch  long,  very  minutely  pubescent,  the  upper  lip  somewhat 
shorter  than  the  lower.     In  woods. 

2.  Scutellaria  pilosa,  Michx.     (L.,pilosus,  hairy.)    HAIRY  SKULLCAP.    Peren- 
nial, clothed  with  spreading  hairs.     Leaves   ovate  to  oval  or  oblong,  crenate  or 
coarsely  serrate,   i   to    3    inches    long,  rather   remote,  the    lower   long-petioled. 
Racemes  short.    Corolla  blue,  about  £  inch  long,  the  lower  lip  a  little  shorter  than 
the  upper.     In  dry  woods  or  thickets. 

3.  Scutellaria  Wrightii,  Gray.     (Latin  genitive  of  proper  name.)     RESINOUS 
SKULLCAP.     Perennial  from  a  woody  root,  6  to  10  inches  high.    Minutely  hairy 


ioo  Introduction  to  Botany. 

and  generally  resiniferous.  Leaves  ovate  to  spatulate-oblong,  entire,  obtuse,  from 
4  to  5  inch  long.  Flowers  solitary  in  the  axils  of  the  upper  leaves.  Corolla  5  to  | 
inch  long,  violet  to  nearly  white,  pubescent.  On  western  plains. 

4.  Scutellaria  parvula,  Michx.     (L.,  parvulus,  very  small.)     SMALL  SKULL- 
CAP.    Perennial  from  slender,  tuberiferous  rootstocks.     Erect  or  ascending,  3  to 
12  inches  high.     Minutely  downy.     Lower  leaves  round-ovate,  upper  lance-ovate. 
Flowers  solitary  in  the  axils  of  the  upper  leaves.     Corolla  |  to  5  inch  long,  violet, 
pubescent.     In  moist,  sandy  soil. 

5.  Scutellaria   campestris,  Britton.     (L.,  campestris,  belonging  to  the  field.) 
PRAIRIE  SKULLCAP.     Perennial  from  tuberous-thickened  rootstocks.     More  or 
less   spreading.     Leaves  ovate,  rounded  or  truncate  at  the  base,   often  dentate. 
Minutely  pubescent.     Flowers  violet  or  purple.     Listed  by  Gray  as  var.  mollis  of 
the  preceding  species.     In  dry,  sandy  soil. 

6.  Scutellaria  nerv6sa,  Pursh.     (L.,  nervosus,  full  of  nerves.)    VEINED  SKULL- 
CAP.    Perennial  from  slender  stolons.     Slender,  8  inches  to  2  feet  high.     Lower 
leaves  rounded  to  ovate,  coarsely  serrate  or  dentate,  upper  leaves  ovate-lanceolate 
and  entire.    Flowers  solitary  in  the  axils  of  the  upper  leaves.     Leaves  prominently 
nerved  beneath.     Corolla  bluish,  about  J  inch  long.     Lower  lip  longer  than  the 
concave  upper  one.    In  moist  thickets  or  woods. 

II.  NEPETA.    Cat  Mint. 

(The  Latin  name.) 

Erect  or  creeping  herbs.  Flowers  in  verticillate  clusters.  Calyx 
tubular,  obliquely  5-toothed.  Corolla  2-lipped,  the  upper  lip  erect, 
2-cleft,  or  notched,  somewhat  concave ;  the  lower  lip  3-cleft  and  spread- 
ing. Stamens  4,  ascending  close  to  the  upper  lip,  didynamous,  the 
lower  pair  shorter.  Anthers  approximate  in  pairs. 

i.  Nepeta  Glech6ma,  Bentham.  (Gr.;  glechon,  pennyroyal.)  GROUND  IVY. 
GlLL-OVER-THE-GROUND.  Perennial,  pubescent,  creeping  and  trailing.  Leaves 
round-kidney-shaped,  green  both  sides,  petioled,  crenate.  Corolla  light  blue,  2  or 
3  times  longer  than  the  calyx.  In  damp  or  shady  places. 

III.   LAMIUM.    Dead  Nettle. 

(Gr. ,  laimos,  throat,  alluding  to  the  ringent  corolla.) 

Mostly  diffuse  annual  or  perennial  herbs.  Leaves  commonly  heart- 
shaped  in  general  outline,  and  crenate,  dentate,  or  entire.  Flowers 
verticillate  in  axillary  or  terminal  clusters.  Calyx  tubular-campanulate, 
with  5  equal  or  unequal  teeth,  and  about  5-nerved.  Tube  of  the  corolla 
longer  than  the  calyx,  dilated  in  the  throat,  2-lipped ;  the  upper  lip  con- 
cave and  generally  entire,  narrowed  at  the  base ;  the  lower  lip  spread- 
ing, 3-lobed,  the  middle  lobe  emarginate.  Stamens  4,  didynamous, 
close  under  the  upper  lip,  approximate  in  pairs,  the  anterior  pair 
longer. 


Dicotyledones.  101 

i.  Lamium  amplexicaule,  L.  (L.,  amplexus,  an  encircling;  caulis,  stock  or 
stem.)  GREATER  HENBIT  or  HENBIT  DEAD  NETTLE.  Slender,  ascending  or 
decumbent  annual  or  biennial,  6  to  18  inches  long.  Leaves  nearly  orbicular, 
coarsely  crenate-toothed,  the  lower  petioled,  the  upper  sessile  and  clasping. 
Flowers  purple,  few  and  small  in  terminal  and  axillary  clusters.  Calyx  nearly  as 
long  as  the  slender  tube  of  the  corolla.  Upper  lip  of  the  corolla  pubescent  and 
the  lower  lip  spotted.  In  fields  and  waste  places. 


IV.  SALVIA.    Sage. 

(The  Latin  name,  from  salvus,  safe,  alluding  to  the  healing  properties.) 

Mostly  herbs,  with  clustered  and  generally  showy  flowers.  Calyx 
2-lipped,  the  upper  lip  3-toothed  or  entire,  the  lower  2-cleft  or  toothed. 
Corolla  deeply  2-lipped,  the  upper  lip  mostly  entire,  straight  or  curved, 
concave  ;  the  lower  lip  spreading  or  pendent,  3-lobed.  Stamens  2,  the 
filaments  short,  surmounted  by  long  filiform  connectives  which  bear  a 
perfect  anther-sac  at  their  upper  ends,  and  only  a  rudimentary  anther- 
sac  or  none  at  all  at  their  lower  ends  (see  p.  188,  Fig.  105).  Style 
2-cleft.  Nutlets  smooth. 

1.  Salvia  lyrata,  L.     (Gr.,  lyra,  lyre.)     LYRE-LEAVED  SAGE.     Perennial  or 
biennial,  more  or  less  pubescent  or  hirsute,  i  to  3  feet  high.     Basal  leaves  petioled, 
tufted,  often  lyre-shaped  or  sinuate-pinnatifid.    Stem  leaves  sessile,  narrower,  often 
entire,  and  seldom  more  than  a  single  pair.     Flowers  in  loose  whorls  forming  an 
interrupted  raceme.    Calyx  campanulate,  the  teeth  of  the  lower  lip  longer  than 
those  of  the  upper.     Corolla  blue  purple,  pubescent,  about  i  inch  long,  upper  lip 
short  and  straight,  smaller  than  the  lower  lip.    Both  anther-cells  pollen-bearing. 
In  woods,  thickets,  and  meadows. 

2.  Salvia  lanceolata,  Willd.     (L.,  lanceolatus,  provided  with  a  little  spear.) 
LANCE- LEAVED  SAGE.    Erect  or  diffuse  annual,  6  to  18  inches  tall,  branched  and 
very  leafy.     Leaves  lanceolate  to  linear-oblong,  narrowing  to  a  petiole,  sparingly 
serrate  or  entire.    Flowers  opposite  or  in  interrupted,  slender,  spikelike  racemes. 
Upper  lip  of  the  calyx  entire,  the  lower  2-cleft.     Corolla  blue,  about  j  inch  long,  the 
lower  lip  about  twice  as  long  as  the  upper.     Lower  end  of  the  connective  not 
anther-bearing,  dilated.    On  our  western  plains. 


SOLANACEJE.    NIGHTSHADE  FAMILY. 

Mostly  herbs,  sometimes  vines  or  shrubs,  with  leaves  usually  alter- 
nate and  without  stipules.  Calyx  gamosepalous,  mostly  5-lobed. 
Corolla  gamopetalous,  salver-form  or  tubular  to  campanulate  or  rotate. 
Stamens  generally  5,  inserted  on  the  tube  of  the  corolla  and  alternate 
with  its  lobes.  Corolla  generally  plaited  in  the  bud.  Ovary  superior, 


IO2  Introduction  to  Botany. 

entire,  2-celled,  rarely  3~5-celled.  Ovules  numerous  on  axillary  pla- 
centae which  often  project  prominently  into  the  cell.  Often  rank-scented 
and  poisonous. 

V.  SOLANUM.    Nightshade. 

(Low  Latin  name  for  nightshade.) 

Herbs  or  shrubs.  Flowers  mostly  cymose,  umbellate,  or  racemose, 
yellow,  white,  bluish,  or  purplish.  Calyx  campanulate  or  rotate,  5- 
toothed  or  cleft.  Corolla  rotate,  5-lobed  or  angled.  Stamens  inserted 
on  the  throat  of  the  corolla,  the  anthers  connate  or  connivant,  oblong, 
each  cell  opening  by  a  terminal  pore,  or  by  a  longitudinal  slit.  Ovary 
and  berry  generally  2-celled. 

1.  Solanum  Carolinense,  L.    HORSE  NETTLE  or  APPLE  OF  SODOM.    Peren- 
nial, green,  beset  with  4-8-rayed  stellate  hairs,  and  armed  with  straight,  yellow 
prickles.    Leaves  oblong-ovate,  sinuate-toothed  or  pinnatifid.    Flowers  racemose, 
violet  or  white.     Lobes  of  the  calyx  lanceolate  or  ovate,  acuminate,  about  half  the 
length  of  the  corolla.    Berries  orange-yellow,  about  f  inch  in  diameter.    In  fields 
or  waste  places. 

2.  Solanum  rostratum,  Dunal.     (L.,  restrains,  beaked.)    SAND  BUR  or  TEXAS 
THISTLE.    Annual,  densely  armed  with  awl-shaped  prickles  and  beset  with  5-8- 
rayed  stellate  hairs.     Leaves  deeply  lobed  or  pinnatifid.    Calyx  very  prickly,  inclos- 
ing the  berry.    Corolla  yellow,  about  i  inch  broad.      One  anther  much  exceeding 
the  others  in  length  and  diameter.    On  our  western  prairies  and  in  waste  places. 

3.  Solanum  Dulcamara,   L.      (L.,  dulcis,  sweet;    amarus,  bitter.)      BITTER- 
SWEET or  NIGHTSHADE.   Perennial  with  climbing  or  rambling  stems,  woody  below. 
Leaves  ovate  or  heart-shaped,  the  upper  leaves  often  halberd-shaped,  or  with  2 
leaflets  or  more  at  the  base.     Corolla  deeply  5-cleft,  violet-purple,  with  greenish 
spots  at  the  base  of  the  lobes.    Berries  red,  oval  or  globose.     In  thickets  or  moist 
places. 

VI.  LYCIUM.    Matrimony  Vine. 
(Named  from  the  country  of  Lycia.) 

Low  shrubs,  or  woody  trailing  or  climbing  plants,  generally  spiny. 
Leaves  small,  alternate,  entire,  often  clustered  on  lateral  spurs.  Flowers 
solitary  or  clustered,  purple,  greenish,  or  white.  Calyx  3-5-toothed  or 
lobed,  persisting,  but  not  enlarging.  Corolla  mostly  funnel-form  or 
salver-form,  5-lobed.  Stamens  5,  the  anthers  dehiscing  longitudinally. 
Style  filiform,  stigma  capitate.  Ovary  and  small,  globose  berry  2-celled. 

i.  Lycium  vulgare,  Dunal.  (L.,  vulgaris,  common.)  COMMON  MATRIMONY 
VINE  or  BOX-THORN.  Often  somewhat  spiny.  Stems  lithe,  trailing,  climbing,  or 
recurved.  Leaves  oblong-spatulate  or  lanceolate.  Flowers  axillary,  solitary  or 
few-clustered  on  slender  pedicels.  Corolla  funnel-form,  purplish  to  greenish. 
Berry  orange-red,  oval.  In  thickets  or  waste  places. 


Dicotyledones.  103 


SCROPHULARIACE^E.    FIGWORT  FAMILY. 

Mostly  herbs.  Flowers  with  a  2-lipped  or  otherwise  irregular  gamo- 
petalous  corolla  and  2,  4,  or  5,  often  didynamous  stamens  inserted  on  the 
corolla  tube.  Calyx  generally  4~5-toothed  or  cleft.  Ovary  superior, 
2-celled,  entire  or  sometimes  2-lobed,  ovules  several  to  many  on  axillary 
placentae.  Style  simple  and  slender,  entire  or  2-lobed. 

I.  PENTSTEMON.     Beardtongue. 

(Gr.,jpente,  five,  stemon,  stamen,  the  fifth  stamen  being  present,  though  sterile.) 

Perennial  herbs,  branching  from  the  base,  with  leaves  usually  oppo- 
site or  verticillate,  the  upper  sessile  and  often  clasping.  Flowers  showy, 
white,  purplish,  or  red,  racemose  or  paniculate.  Calyx  5-parted. 
Corolla  mostly  tubular-inflated,  2-lipped,  the  upper  lip  2-lobed,  under 
lip  3-lobed.  Stamens  5,  4  anther-bearing  and  didynamous,  and  i  sterile, 
either  naked  or  bearded.  Style  filiform  and  stigma  terminal.  Capsule 
oblong  to  globose,  containing  many  seeds. 

1.  Pentstemon  pubescens,  Soland.     (L.,  pubescens,  hairy.)     HAIRY  BEARD- 
TONGUE.     Stems  slender  and  pubescent,  I  to  3  feet  high.     Leaves  varying  from 
ovate  and  petioled  below  to  lanceolate  and  sessile  above.      Inflorescence  loose, 
glandular-pubescent.    Beard  at  the  base  of  the  lower  lip  nearly  closing  the  throat 
of  the  purplish  to  whitish  corolla.     Sterile  filament  bearded  for  about  half  its  length. 
In  dry  woods  or  rocky  grounds. 

2.  Pentstemon   Digitalis,   Nutt.     (L.,  digitalis,   finger-shaped.)     FOXGLOVE 
BEARDTONGUE.     Stem  2  to  5  feet  high.    Glabrous  below,  but  inflorescence  glandu- 
lar-pubescent.    Lower  leaves  oblong-oval,  narrowing  below.     Upper  leaves  ovate- 
lanceolate  to  lanceolate,  sessile,  and  somewhat  clasping.    Corolla  white,  slightly 
2-lipped,  open  in  the  throat,  i  inch  or  more  long.    Upper  part  of  sterile  filament 
bearded.     In  fields  and  thickets. 

3.  Pentstemon  gracilis,  Nutt.      (L.,  gracilis,  slender.)      SLENDER  BEARD- 
TONGUE.    6  to  18  inches  tall,  glabrous  below,  but  the  lax  inflorescence  glandular- 
pubescent.      Lower    leaves   linear-oblong  to   spatula te.       Upper    leaves    mostly 
linear-lanceolate.    Corolla  purple  or  whitish,  \  to  i  inch  long,  tubular-funnel-form, 
open  in  the  throat.     Sterile  filament  bearded  above  for  about  £  of  its  length.     On 
moist  prairies. 

4.  Pentstemon  Cobaea,  Nutt.    (From  proper  name,  Cob6,  a  Spanish  botanist.) 
COB^A  BEARDTONGUE.      Stems  stout,  i  to  2  feet  high,  soft-pubescent  beneath 
and  glandular-pubescent  above.     Leaves  ovate  to  oblong-ovate  or  ovate-lanceolate, 
often  sharply  dentate,  the  upper  clasping.     Corolla  sometimes  2  inches  long,  much 
inflated  above  the  middle,  whitish  or  purplish,  its  lobes. about  equal,  rounded  and 
spreading.    Sterile  filament  bearded.     On  dry  prairies. 


104  Introduction  to  Botany. 


II.  VERONICA.    Speedwell. 

(Possibly  named  for  St.  Veronica.) 

Chiefly  herbs,  with  opposite  or  sometimes  alternate  or  verticillate 
leaves.  Flowers  usually  small,  inflorescence  racemose,  spicate,  or  soli- 
tary. Calyx  mostly  4-parted,  sometimes  3-  or  5-parted.  Corolla  rotate 
or  salver-form,  generally  with  a  4-parted  border,  the  upper  lobe  com- 
monly broader  than  the  others.  Stamens  2,  exserted  and  divergent, 
inserted  on  each  side  of  the  upper  lobe  of  the  corolla.  Capsule  flattened, 
notched  or  obtuse  at  the  apex,  2-celled,  few-  to  many-seeded.  Style 
and  stigma  simple. 

1.  Veronica  officinalis,  L.     (L.,  officina,  workshop.)    COMMON  SPEEDWELL. 
Pubescent.    Stems  ascending  or  prostrate,  rooting  at  the  base,  3  to  10  inches  long. 
Leaves  mostly  obovate,  serrate,  short-petioled.      Racemes  spikelike  and  many- 
flowered.    Flowers  pale  blue,  about  \  inch  broad.    Capsule  much  flattened  and 
broadly  notched.     Perennial.     In  dry  fields  and  open  woods. 

2.  Veronica    serpyllif61ia,    L.       (L.,    serpyllum,   wild    thyme;   folium,  leaf.) 
THYME-LEAVED  SPEEDWELL.     Perennial.    Glabrous  or  softly  pubescent.     De- 
cumbent at  the  base,  much  branched,  the  branches  ascending  or  erect,  2  to  10 
inches  high.    Leaves  mostly  petioled,  oblong,  oval  or  ovate,  crenate,  those  of  the 
inflorescence  lanceolate.     Inflorescence  a  terminal,  spicate,  loose-flowered  raceme. 
Corolla  pale  blue  with  dark  stripes,  or  white,  about  g  inch  broad.     Capsule  broader 
than  long,  obcordate,  or  emarginate.     Roadsides,  fields,  and  thickets. 

3.  Veronica  peregrina,  L.     (L.(  peregrinus,  foreign,  or  exotic.)     PURSLANE 
SPEEDWELL  or  NECKWEED.      Nearly  smooth  or  glandular-puberulent  annual. 
Erect  or  ascending,  3  to  12  inches  high.     Lowest  leaves  oval-oblong,  short-petioled, 
or  sessile,  toothed,  thickish.     Upper  leaves  mostly  oblong  or  spatulate,  longer  than 
the  solitary  flowers  in  their  axils.     Corolla  minute,  whitish.     Capsule  obcordate, 
nearly  orbicular,  shorter  than  the  calyx.     In  moist  waste  and  cultivated  grounds. 

4.  Veronica  arvensis,  L.     (L.,  arvum,  a  field.)    CORN  or  WALL  SPEEDWELL. 
Slender,  pubescent  annual,  simple  or  diffusely  branched,  3  to  10  inches  tall.    Lowest 
leaves  petioled,  ovate,  and  crenate.    Upper  leaves  ovate  to  lanceolate,  frequently 
alternate  and  entire  with  a  minute  blue  or  nearly  white  flower  on  a  short  pedicel  in 
the  axil  of  each.     Capsule  minute,  broadly  obovate  or  obcordate.     In  cultivated 
grounds,  fields,  woods,  or  waste  places. 

HI.  CASTILLEIA.    Painted  Cup. 

(Named  for  Castillejo,  Spanish  botanist.) 

Herbs.  Parasitic  on  the  roots  of  other  plants.  Leaves  alternate, 
entire  or  cut-lobed.  Flowers  red,  purple,  white,  or  yellow,  in  leafy 
bracted  spikes,  the  bracts  being  often  expanded  and  more  brightly  col- 
ored than  the  flowers.  Calyx  tubular,  somewhat  compressed  laterally, 


Dicotyledones.  105 

cleft  on  the  upper  and  sometimes  on  the  lower  side.  Corolla  2-lipped, 
the  upper  lip  elongated,  compressed  laterally,  sometimes  curved  and 
keeled ;  the  lower  lip  short  and  3-lobed.  Stamens  4,  didynamous,  in- 
closed in  the  upper  lip  of  the  corolla.  Capsule  many-seeded;  style 
filiform,  and  stigma  entire  or  2-lobed. 

1.  Castilleia  coccinea,  Sprang.     (L.,  coccineus,  of  a  scarlet  color.)     SCARLET 
PAINTED  CUP  or  INDIAN  PAINT-BRUSH.    Slender  annual  or  biennial,  i  to  2  feet 
high,  villous-pubescent.    Basal  leaves  tufted,   obovate  or  oblong,  mostly  entire. 
Stem  leaves  3-5-cleft  into  linear  or  lanceolate  segments.    Bracts  of  the  inflorescence 
brilliant  scarlet,  or  rarely  yellow.    Corolla  greenish  yellow,  its  tube  included  within 
the  2-cleft  calyx.     In  low  meadows  and  moist  thickets. 

2.  Castilleia  sessiliflora,  Pursh.    (L.,  sessilis,  low-growing ;  flos,  floris,  flower.) 
DOWNY  PAINTED  CUP.     Densely  leaved  perennial,  6  to  15  inches  tall,  clothed  with 
a  fine  cinereous  pubescence.     Lower  leaves  commonly  linear  and  entire,  the  upper 
deeply  cleft  into  narrow,  entire,  or  cleft  lobes.     Bracts  of  the  inflorescence  not  bril- 
liantly colored,  green.     Lobes  of  the  calyx  linear-lanceolate.     Corolla  yellowish, 
nearly  2  inches  long,  its  lower  lip  narrowly  lobed.     On  prairies. 

IV.  PEDICULARIS.    Lousewort. 
(L.,pediCTtlus,  louse;  application  not  evident.) 

Herbs,  with  pinnately-lobed,  cleft,  or  divided  leaves,  mostly  lanceolate 
or  linear  in  general  outline.  Flowers  in  terminal  spikes  or  spicate 
racemes.  Calyx  tubular,  variously  cleft  or  toothed.  Corolla  2-lipped, 
with  cylindric  tube ;  the  upper  lip  laterally  flattened,  curved,  and  some- 
times beaked ;  lower  lip  erect,  with  3  spreading  lobes.  Stamens  4, 
didynamous,  within  the  upper  lip  ;  anther-sacs  equal.  Capsule  ovate  or 
lanceolate,  generally  oblique,  several-seeded. 

i.  Pedicularis  Canadensis,  L.  WOOD  BETONY  or  LOUSEWORT.  Hairy 
perennial  with  generally  clustered  stems  6  to  18  inches  high.  Lower  leaves  oblong, 
slender-petioled,  pinnately-lobed  or  parted,  the  lobes  variously  toothed.  Flowers 
in  short  spikes  which  become  elongated  in  fruit.  Calyx  cleft  on  the  lower  side. 
Corolla  usually  greenish  yellow  or  purplish,  about  5  inch  long;  upper  lip  arched, 
with  2  minute  teeth  near  the  apex.  Capsule  lanceolate  and  flat.  On  banks  and  in 
thickets. 

LENTIBULARIACE^.    BLADDERWORT  FAMILY. 

Herbs,  growing  in  water  or  in  wet  places,  either  floating  or  rooted. 
Flowers  irregular,  solitary  or  racemose,  borne  on  erect  scapes.  Calyx 
2-lipped.  Corolla  2-lipped  and  personate,  the  upper  lip  usually  erect 
and  concave;  lower  lip  3-lobed,  spreading,  forming  a  nectariferous  spur 
below.  Stamens  2,  with  confluent  anther-sacs.  Ovary  superior, 


io6  Introduction  to  Botany. 

i -celled,  with  numerous  ovules  on  a  free,  central  placenta.  Stigma  1-2- 
lipped,  either  sessile  or  borne  on  a  short  style.  Capsules  bursting 
irregularly  or  dehiscing  by  valves. 

I.  UTRICULARIA.    Bladderwort. 

(L.,  utriculus,  a  little  bladder.) 

Herbs,  either  floating  free  or  rooted,  the  aquatic  species  having  finely 
dissected  leaves  bearing  numerous  small  bladders  which  are  bristled 
at  the  orifice.  Flowers  few  or  solitary  on  slender  scapes,  prominently 
personate.  (See  Fig.  73,  p.  145.) 

1.  Utricularia  vulgaris,  L.    (L.,  vulgaris,  common.)    GREATER  BLADDER- 
WORT  or  HOODED  WATER  MILFOIL.    Floating  free,  the  branches  becoming  some- 
times i  foot  long.    Scapes  3  to  14  inches  high  with  few  or  no  scales.     Divisions  of 
the  leaves  capillary,  bearing  numerous  bladders.     Racemes  3-20- flowered.    Corolla 
yellow,  about  \  inch  broad,  the  spur  conic  and  somewhat  curved,  shorter  than  the 
slightly  3-lobed  lower  lip.    Pedicels  recurved  in  fruit.     In  ponds  and  slow  streams. 

2.  Utricularia  minor,  L.     (L.,  minor,  smaller.)      LESSER    BLADDERWORT. 
Floating  free.     Leaves  scattered,   dichotomously  branched  into  a  few  setaceous 
divisions.    Bladders  among  the  leaves,  few  and  often  none.    Scapes  slender,  3  to  7 
inches  high,  bearing  i-io  flowers.    Corolla  pale  yellow,  \  inch  broad  or  less.    Spur 
very  much  reduced,  or  hardly  apparent.     Pedicels  recurved  in  fruit.     In  bogs  and 
shallow  ponds. 

OROBANCHACE^.    BROOM  RAPE  FAMILY. 

Root  parasites,  from  nearly  white  to  brownish  or  purplish,  with 
leaves  reduced  to  scales,  and  irregular,  perfect  flowers,  which  are  ses- 
sile in  spikes  or  peduncled  and  solitary  in  the  axils  of  scales.  Calyx 
gamosepalous,  4-5-toothed  or  cleft,  sometimes  divided  on  one  or  both 
sides.  Corolla  gamopetalous,  more  or  less  2-lipped,  the  upper  lip  2- 
lobed  or  entire,  lower  lip  3-lobed  ;  throat  of  the  tubular  corolla  ringent. 
Stamens  4,  didynamous,  alternate  with  the  lobes  of  the  corolla  and 
inserted  on  its  tube.  Ovary  superior  and  i-celled,  with  numerous 
ovules -on  2-4-parietal  placentae.  Capsule  i -celled  and  2-valved. 

I.  APHYLLON.    Naked  Broomrape. 
(Gr.,  a,  without;  phyllon,  leaf.) 

Brownish  or  whitish  herbs.  Scapes  naked.  Flowers  purplish  or 
whitish  on  long,  glandular-pubescent  peduncles.  Calyx  campanulate, 
about  equally  5-cleft.  Corolla  somewhat  2-lipped,  the  upper  lip  2-lobed 
and  the  lower  3-lobed.  Stamens  included.  The  4  placentas  equidistant 
or  grouped  in  pairs. 


Dicotyledones.  107 

1.  Aphyllon   unifldrum,  Gray.     (L.,  unus,   one;   flos,  floris,  flower.)     ONE- 
FLOWERED  BROOMRAPE  or  CANCER  ROOT.    Stem  hardly  appearing  above  the 
ground,  and  sending  up  i-flowered,  scapelike  peduncles,  3  to  8  inches  high.     Calyx 
less  than  5  the  length  of  the  corolla,  its  divisions  awl-shaped.     Corolla  about  i 
inch  long,  white  to  violet,  its  lobes  obovate  and  short,  and  tube  slightly  curved. 
Placentae  equidistant.     In  damp  woods,  on  the  roots  of  various  plants. 

2.  Aphyllon  fasciculatum,   Gray.     (L.,  fasciculus,  a  small  bundle.)     CLUS- 
TERED BROOMRAPE  or  CANCER  ROOT.    Stems  2  to  4  inches  high,  glandular- 
pubescent,  bearing  3  to  15  i-flowered  peduncles.     Corolla  purplish  yellow,  plainly 
2-lipped.     In  sandy  soil,  parasitizing  the  roots  of  various  plants. 

n.  CONOPHOLIS.    Squaw  Root  or  Cancer  Root. 

(Gr.,  konos,  cone;  pholis,  scale.) 

Light  brown,  scaly  herb,  parasitic  on  the  roots  of  trees.  Flowers 
in  dense,  scaly  spikes.  Calyx  irregularly  5-toothed,  split  down  the 
lower  side,  subtended  by  2  bractlets.  Corolla  2-lipped,  its  tube  slightly 
curved ;  upper  lip  nearly  erect,  concave,  notched  at  the  summit ;  lower 
lip  shorter,  3-lobed  and  spreading.  Stamens  exserted  ;  anthers  pubes- 
cent. The  4  placentae  about  equidistant. 

i.  Conopholis  Americana,  Wallr.  SQUAW  ROOT.  Stems  usually  clustered, 
3  to  10  inches  high,  light  brown,  covered  with  overlapping  scales,  lower  scales  much 
shorter  than  the  upper.  Flowers  about  \  inch  long;  corolla  pale  yellow.  Among 
fallen  leaves  in  rich  woods. 

BIGNONIACE^E.     BIGNONIA  or  TRUMPET  CREEPER  FAMILY. 

Shrubs  or  trees  or  woody  vines.  Leaves  generally  opposite.  Flowers 
large,  clustered,  more  or  less  irregular.  Calyx  2-lipped,  5 -cleft,  or  entire. 
Corolla  gamopetalous,  more  or  less  funnel-form,  tubular,  or  campanulate, 
sometimes  2-lipped.  Anther-bearing  stamens,  2  or  4  and  didynamous, 
alternate  with  the  lobes  of  the  corolla  and  inserted  on  its  tube.  Ovary 
superior,  often  2-celled  by  ingrowth  of  the  placentas  or  projections  from 
them ;  many-ovuled.  Fruit,  a  dry  capsule.  Seeds  flat  and  winged. 

I.  BIGNONIA.    Cross  Vine  or  Tendriled  Trumpet  Flower. 

(Named  for  Abte  Bignon.) 

Tall,  woody  climber,  with  compound  leaves  ending  in  a  tendril. 
Calyx  short,  somewhat  5-toothed  or  undulate.  Corolla  gamopetalous, 
inflated  above  the  calyx,  5-lobed,  somewhat  2-lipped.  Perfect  stamens 
4,  didynamous,  included.  Capsule  linear,  flattened  parallel  with  the 
partition.  Seeds  transversely  winged. 


io8  Introduction  to  Botany. 

i.  Bignonia  capreolata,  L.  (L.,  capreolus,  small  tendril.)  CROSS  VINE. 
Leaves  long-petioled,  2-foliate,  ending  with  a  tendril;  leaflets  oblong-ovate. 
Corolla  2  inches  long,  orange-red,  puberulent  without,  yellow  on  the  inside.  Pod 
about  6  inches  long. 

II.  CATALPA.    Catalpa  or  Indian  Bean  or  Candle  Tree. 

(The  aboriginal  Indian  name.) 

Trees  or  sometimes  shrubs,  with  mostly  opposite,  simple,  petioled, 
ovate,  or  cordate  leaves  and  showy  white  or  mottled  flowers.  Tube  of 
the  corolla  much  swollen,  its  limb  5-lobed  and  2-lipped.  Perfect  sta- 
mens 2,  or  sometimes  4.  Capsule  cylindric,  long  and  slender,  2-celled. 
Seeds  flat,  with  lateral  wings  fringed  on  the  border. 

1.  Catalpa  Bignonioides,  Walt.     (From  proper  name  Bignon,  and  Gr.,  eidos, 
form.)     CATALPA.     Tree  with  thin  bark.    Leaves  mostly  broadly  ovate  and  entire, 
acute  or  acuminate,  strong  scented.     Corolla  much  spotted  within,  the  lower  lobe 
entire.     Often  planted  for  shade  tree.     In  woods  in  the  Gulf  States. 

2.  Catalpa  speciosa,  Warder.     (L.,  speciosus,  showy.)     CATALPA.     Tree  with 
thick  and  rough  bark.     Leaves  much  as  in  the  last  species,  but  without  strong 
scent.     Corolla  little  mottled  within,  the  lower  lobe  emarginate.     In  rich  woods. 
Often  planted. 

ACANTHACE-ffi.    ACANTHUS  FAMILY. 

Mostly  herbs,  with  opposite,  simple  leaves  and  regular,  or  only 
slightly  irregular,  perfect  flowers.  Calyx  4~5~parted  or  cleft,  persistent. 
The  gamopetalous  corolla  5-lobed,  nearly  regular,  or  somewhat  2-lipped. 
Perfect  stamens  4,  and  didynamous,  or  only  2.  Ovary  superior,  2-celled, 
with  2-1  o  ovules  in  each  cavity.  Seeds  borne  on  curved  projections 
from  the  placentae.  Capsule  2-celled,  opening  elastically  by  2  valves 
on  drying. 

I.   RUELLIA. 
(Named  for  John  Ruelle,  herbalist.) 

Perennial  herbs  or  shrubs,  with  entire,  or  rarely  dentate,  leaves  and 
large,  solitary  or  clustered  flowers  in  the  axils  of  the  leaves,  or  terminal. 
Calyx  5-cleft  or  parted.  Corolla  funnel-form  or  salver-form,  with  large, 
spreading  border.  Stamens  4.  Ovules  3-10  in  each  cavity  of  the  ovary. 
Style  recurved  toward  the  apex. 

i.  Ruellia  strepens,  L.  (L.,  strepens,  murmuring  ;  application  not  evident.) 
SMOOTH  RUELLIA.  Smooth  or  slightly  pubescent  perennial,  i  to  4  feet  high. 
Leaves  oblong-ovate  or  oval  on  short  petioles.  Flowers  solitary  or  clustered  in 
the  axils.  Divisions  of  the  calyx  linear-lanceolate.  Corolla  blue,  about  i|  to  2 


Dicotyledones.  109 

inches  long,  the  diameter  of  the  corolla  about  equaling  the  tube.     Capsule  longer 
than  or  equaling  the  calyx.     In  rich  soil  or  dry  woods. 

2.  Ruellia  ciliosa,  Pursh.  (L.,  cilium,  an  eye-lash.)  HAIRY  RUELLIA. 
Rather  stout,  i  to  2|  feet  high,  beset  with  soft,  whitish  hairs.  Leaves  oval  or  ovate- 
oblong,  sessile  or  short-petioled.  Flowers  solitary  or  clustered  in  the  axils. 
Corolla  blue  to  violet-purple,  its  tube  i£  to  2  inches  long.  Capsule  shorter  than 
the  calyx.  In  dry  soil. 

II.  DIANTHERA.    Water  Willow. 

(Gr.,  dis,  double;  anther  a,  anther,  alluding  to  the  separated  anther  cells.) 

Mostly  perennial  herbs,  growing  in  wet  places.  Leaves  opposite 
and  entire.  Flowers  very  irregular,  purplish,  in  axillary,  peduncled 
spikes  or  heads.  Calyx  5-parted ;  corolla  2-lipped,  the  upper  lip  erect, 
concave,  2-toothed ;  lower  lip  spreading  and  3-cleft.  Stamens  2, 
inserted  on  the  throat  of  the  corolla.  Each  cavity  of  the  ovary 
containing  2  ovules. 

i.  Dianthera  Americana,  L.  DENSE-FLOWERED  WATER  WILLOW.  Erect, 
smooth  perennial,  i  to  2  feet  high,  with  lanceolate  or  linear-lanceolate  leaves. 
Flowers  violet  to  nearly  white,  in  short,  long-peduncled  spikes.  Tube  of  the 
corolla  shorter  than  the  lips.  In  water  and  wet  places. 

PLANTAGINACE^J.     PLANTAIN  FAMILY. 

Chiefly  acaulescent  or  short-stemmed  annuals  or  perennials.  Leaves 
mainly  basal,  with  prominent  parallel  ribs.  Flowers  chiefly  in  spikes 
or  heads  on  long  scapes.  Calyx  4-parted.  Corolla  4-lobed,  membra- 
naceous.  Stamens  mostly  4,  inserted  on  the  tube  of  the  corolla  and 
alternate  with  its  lobes.  Ovary  superior,  i-2-celled,  or  falsely  3-4- 
celled,  with  i -several  ovules  in  each  cavity. 

I.  PLANTAGO.    Plantain. 

(The  Latin  name.) 

Short-stemmed  or  acaulescent  herbs,  with  mostly  prominently  ribbed 
leaves  and  greenish  or  purplish  flowers  in  spikes  on  slender  scapes. 
Calyx  of  4  membranous-margined  sepals,  persistent.  Corolla  salver- 
form  or  rotate,  4-parted,  withering  on  the  pod.  Stamens  mostly  4, 
sometimes  2,  exserted.  Ovary  generally  2-celled,  with  I  or  more 
ovules  in  each  cell.  Capsule  with  circumscissile  clehiscence. 

i.  Plantago  major,  L.  (L.,  major,  larger.)  COMMON  or  GREATER  PLAN- 
TAIN. Perennial.  Scapes  sometimes  becoming  2  feet  tall,  longer  than  the  leaves. 
Spikes  dense,  linear-cylindric.  Withered  corolla  not  closing  over  the  capsule  in 
fruit.  Leaves  on  long  petioles,  mostly  ovate,  with  3  to  n  ribs,  which  remain  free 


no  Introduction  to  Botany. 


to  the  base.     Flowers  proterogynous,  stamens  4.    Capsule  about  twice  the  length  of 
the  calyx.     Seeds,  several  in  the  capsule.     In  yards  and  waste  places. 

2.  Plantago  lanceolata,  L.     (L.,  lanceolatus ,  armed  with  a  little  lance.)     RIB- 
GRASS  or  ENGLISH  PLANTAIN.    Somewhat  hairy  perennial  or  biennial,  with  oblong- 
lanceolate  leaves  tapering  to  a  petiole;    ribs  of  the  leaves  3-5,  free  to  the  base. 
Scapes  exceeding  the  leaves,  becoming  sometimes  2  feet  tall.     Spikes  at  first  short 
and  dense,  becoming  later  cylindric.    Sepals  with  green  midrib,  and  scarious  on 
the  margins.     Capsule  2-seeded,  somewhat  longer  than  the  calyx.     In  fields  and 
waste  places. 

3.  Plantago  cordata,  Lam.     (L.,  cordatus,  heart-shaped.)     HEART-LEAVED 
or  WATER  PLANTAIN.     Glabrous  perennial.     Leaves  ovate  to  orbicular,  pinnately 
veined,  cordate  or  abruptly  narrowed  at  the  base,  long-petioled.     Scapes  exceeding 
the  leaves ;  spikes  becoming  loosely  flowered.     Bracts  fleshy.     Capsule  2~4-seeded. 
Found  in  swampy  places  and  along  streams. 

4.  Plantago  Piirshii,  R.  &  S.     (Latin  genitive  of  proper  name.)     PURSH'S 
PLANTAIN.      (Plantago    Patagonica,  var.  gnaphalioides ,   in   Gray's    "  Manual.") 
Woolly  or  hairy  annual,  with  slender  scapes  and  linear  leaves.     Spikes  dense, 
cylindric,  and  very  woolly;  bracts  equaling  or  only  slightly  exceeding  the  flowers. 
Capsule  2-seeded,  but  little  exceeding  the  calyx.     On  dry  prairies. 

5.  Plantago  aristata,  Michx.     (L.,  aristatus,  having  ears.)     LARGE-BRACTED 
PLANTAIN.    Villous  or  glabrate  annual,  with  linear  leaves  and  dense,  cylindric, 
pubescent,  but  not  woolly  spikes.     Bracts  of  the  inflorescence  linear,  ascending, 
many  times  exceeding  the  flowers.     On  dry  plains  or  prairies. 

RUBIACEJE.    MADDER  FAMILY. 

Herbs  or  shrubs,  with  leaves  opposite  or  verticillate,  often  connected 
by  intermediate  stipules.  Flowers  perfect,  but  sometimes  dimorphous. 
Calyx  coherent  with  the  ovary.  Corolla  gamopetalous,  4~5-lobed.  Sta- 
mens as  many  as  the  lobes  of  the  corolla  and  inserted  on  its  tube,  alter- 
nate with  the  lobes.  Ovary  2-4-celled,  with  ovules  solitary  or  many  in 
each  cavity.  Fruit  various. 

I.  HOUSTONIA.    Bluets. 
(Named  for  Dr.  William  Houston,  English  botanist.) 

Mostly  tufted,  erect  or  spreading  herbs,  with  opposite  and  entire, 
sometimes  ciliate  leaves,  and  commonly  dimorphous,  blue,  purple,  or  white 
flowers.  Calyx  4-lobed,  corolla  funnel-form  or  salver-form,  4-lobed. 
Stamens  4.  Ovary  2-celled,  with  several  ovules  in  each  cell.  Style 
slender;  stigmas  2. 

i.  Houstonia  coerulea,  L.  (L.,  cceruleus,  azure.)  BLUETS  or  INNOCENCE. 
Smooth,  with  erect  and  slender  stems  sparingly  branched  from  the  base,  3  to  7 
inches  high.  Lower  leaves  spatulate  or  oblanceolate ;  upper  leaves  oblong-elliptic, 


Dicotyledones.  1 1 1 


about  J  inch  long.  Peduncles  slender,  i  inch  or  more  long.  Corolla  light  blue  to 
nearly  white,  with  yellow  center,  j  to  5  inch  broad.  Perennial  by  slender  rootstock. 
In  grassy  or  moist  places. 

2.  Houstonia    minima,    Beck.      (L.,   minimus,   smallest.)      LEAST  BLUETS. 
Diffuse  or  spreading,  and  generally  rough,  annual,  i  to  z\  inches  high.     Lower 
leaves  spatulate  or  ovate,  upper  leaves  oblong-elliptic  to  nearly  linear.     Peduncles 
i  inch  or  less  long.    Calyx  lobes  rather  broad  and  much  exceeding  the  capsule. 
Corolla  violet  to  purple.     In  dry  soil. 

3.  Houstonia  purpurea,  L.     (L.,  purpureus,  purple.)    LARGE  HOUSTONIA. 
Erect  and  stout,  mostly  glabrous  perennial,  4  to  18  inches  high.     Leaves  ovate  or 
ovate-lanceolate,  sometimes  2  inches  long.     Flowers  in  terminal  cymes  or  cymose 
clusters.      Corolla    funnel-form,   lilac    or  purple.     Calyx  lobes   longer  than  the 
globular  pod.     In  woodlands  or  open  places. 

4.  Houstonia  ciliolata,  Torr.    (L.,ci/ium,  an  eye-lash.)   FRINGED  HOUSTONIA. 
Tufted,  erect  perennial,  4  to  7  inches  tall.     Leaves  oblanceolate  to  obovate,  ciliate- 
fringed.    Corolla  purple  or  lilac.     On  rocky  banks. 

5.  Houstonia    angustifolia,   Michx.      (L.,  angustus,  narrow;  folium,   leaf.) 
NARROW- LEAVED  HOUSTONIA.     Stiff,  erect,  glabrous  perennial,  rising  i  to  2  feet 
from  a  deep  root.    Leaves  mostly  linear,  often  in  fascicled  clusters.     Flowers  on 
short  pedicels  in  dense,  terminal,  cymose  clusters.     Corolla  purplish  to  white,  its 
lobes  bearded  within.     Capsule  compressed-obovoid,  nearly  as  long  as  the  calyx 
lobes.     In  open  places. 

n.  MITCHELLA.    Partridge  Berry. 
(Named  for  Dr.  John  Mitchell,  botanist.) 

Creeping  herbs,  with  opposite,  evergreen  leaves  and  terminal,  dimor- 
phous flowers  in  pairs,  with  united  ovaries.  Calyx  usually  4-toothed. 
Corolla  funnel-form  and  4-lobed.  Stamens  4,  inserted  on  the  throat 
of  the  corolla  alternate  with  its  lobes.  Ovary  4-celled,  with  i  ovule  in 
each  cavity.  Style  exserted  ;  stigmas  4.  Flowers  white  or  tinged  with 
purple,  fragrant.  Fruit,  2  united,  scarlet,  edible  drupes. 

i.  Mitchella  repens,  L.  (L.,  repens,  creeping  or  trailing.)  PARTRIDGE- 
BERRY  or  TWIN-BERRY.  Stems  slender  and  rooting  at  the  nodes.  Leaves  peti- 
oled,  rounded-ovate,  sometimes  variegated  with  white  lines.  Flowers  white  and 
sessile.  Corolla  about  \  inch  long.  Fruit  persisting  through  the  winter.  At  the 
bases  of  trees  in  dry  woods. 

HI.  GALIUM.    Bedstraw  or  Cleavers. 
(Gr.,gaZa,  milk,  which  some  species  have  the  property  of  curdling.) 

Slender  herbs,  with  square  stems  and  whorled  leaves,  and  small 
flowers  in  axillary  or  terminal  cymose  clusters.  Tube  of  the  calyx  some- 
what globose,  its  teeth  minute  or  none.  Corolla  rotate,  mostly  4-parted. 


H2  Introduction  to  Botany. 

Stamens  4,  or  sometimes  3,  exserted.     Ovary  2-celled  with  i  ovule  in 
each  cavity.     Fruit  separating  into  2  i-seeded  carpels. 

1.  Galium  Aparine,  L.     (Gr.,  aparine,  goose-grass.)     CLEAVERS  or  GOOSE- 
GRASS.     Weak  annual ;  the  stem  becoming  2  to  5  feet  long,  beset  with  backward- 
growing  bristles.     Leaves  lanceolate  or  oblanceolate,  i  to  3  inches  long,  about  8  in 
a  whorl,  rough  on  margins  and  midrib.     Flowers  white,  1-3  in  the  axils.    In  shaded 
grounds,  or  habitat  various. 

2.  Galium  circaezans,  Michx.     WILD    LIQUORICE.     Somewhat   pubescent 
perennial,  i  to  2  feet  high.     Leaves  ovate  to  oval-lanceolate,  4  in  a  whorl.     Pe- 
duncles forked ;  corolla  greenish,  hairy  outside.     In  dry  woods. 

CAPRIFOLIACE^.    HONEYSUCKLE  FAMILY. 

Shrubs  and  woody  vines,  or  sometimes  herbs,  with  opposite,  exstip- 
ulate  leaves.  Calyx  3~5-toothed  or  lobed,  its  tube  coherent  with  the 
ovary.  Corolla  gamopetalous,  rotate  to  tubular.  Stamens  5,  or  some- 
times 4,  inserted  on  the  tube  of  the  corolla  alternate  with  its  lobes. 
Ovary  i-6-celled.  Fruit  a  berry,  drupe,  or  capsule. 


I.  SAMBUCUS.    Elder. 

(The  Latin  name.) 

Shrubs,  with  pinnate  leaves  and  serrate  or  laciniate  leaflets,  and 
small,  white  flowers  in  dense,  compound  cymes.  Calyx  tube  3~5-toothed 
or  lobed.  Corolla  somewhat  campanulate,  3~5-lobed.  Stamens  5,  in- 
serted on  the  base  of  the  corolla.  Ovary  3-5-celled.  Stigmas  3. 
Fruit  a  small,  berrylike,  juicy  drupe. 

1.  Sambucus  Canadensis,  L.    COMMON  ELDER.    Nearly  glabrous,  3  to  10 
feet  high.     Younger  stems  with  large,  white  pith.     Leaflets  5-11,  ovate  or  oval,  ser- 
rate, acuminate.     Cymes  broad  and  flat.     Fruit  purple  to  black.    Usually  in  moist 
soil. 

2.  Sambucus  racemosa,  L.    (L.,  racemosus,  full  of  clusters.)     RED-BERRIED 
ELDER.    2  to  12  feet  high,  with  commonly  pubescent  twigs  and  leaves,  and  warty 
bark.     Leaflets  5-7,  ovate-lanceolate,  sharply  serrate.    Cymes  somewhat  pyramidal. 
Fruit  bright  red.     In  rocky  places. 

H.  VIBURNUM. 

(The  Latin  name.) 

Shrubs  or  trees,  with  simple  leaves  and  mostly  white  flowers  in  com- 
pound cymes.  Calyx  5-toothed.  Corolla  deeply  5-lobed,  spreading. 
Stamens  5,  inserted  on  the  tube  of  the  corolla,  exserted.  Ovary  in- 


Dicotyledones.  113 

ferior,  i-3-celled,  with  a  single  ovule  in  each  cell.     Style  short ;  stigmas 
1-3.     Fruit  a  i-celled,  i-seeded  drupe. 

1.  Viburnum  Opulus,  L.     (L.,  opulus,  a  kind  of  maple.)     CRANBERRY-TREE 
or  HiGH-BUSH  CRANBERRY.    Shrub,  becoming  sometimes  12  feet  high.    Branches 
upright  and  smooth.     Leaves  deeply  3-lobed  toward  the  apex,  the  lobes  dentate. 
Marginal  flowers  much  larger  than  the  others.     Drupe  globose,  red,  acid.    In  low 
ground  along  streams. 

2.  Viburnum   pubescens,   Pursh.     DOWNY-LEAVED   ARROW-WOOD.      Low 
branching  shrub,  2  to  5  feet  high.     Leaves  ovate,  coarsely  serrate,  nearly  sessile, 
acute,  soft-pubescent  beneath.     All  the  flowers  perfect.     Drupes  oval  and  nearly 
black.     In  rocky  woods. 

3.  Viburnum  prunifolium,  L.     (L,.,prunus, plum;  folium,  leaf.)     BLACK  HAW, 
STAG- BUSH,  or  SLOE.    Shrub  or  small  tree,  with  ovate  or  oval,  finely  serrate  leaves, 

1  to  3  inches  long,  obtuse  at  the  apex.     Cymes  compound  and  sessile.     Petioles 
hardly  or  not  at  all  margined.    Fruit  ripening  in  the  fall,  oval,  bluish  black,  sweet. 
In  dry  or  moist  soil. 

4.  Viburnum  Lentago,  L.    NANNY-BERRY,  SHEEP-BERRY,  or  SWEET  VIBUR- 
NUM.    Shrub  or  small  tree  with  ovate,  finely  serrate  leaves,  acuminate  at  the  apex, 

2  to  4  inches  long ;  petioles  long  and  often  margined.     Drupes  oval,  bluish  black, 
with  a  bloom.    Cymes  compound  and  sessile.     Along  banks  of  streams  and  in 
woods. 

HI.  TRIOSTEUM. 

(Abbreviation  of  triostesspermum,  from  Gr.,  tri,  three;  osteon,  bone;  sperma,  seed; 
alluding  to  the  three  bony  seeds.) 

Perennial  herbs,  with  opposite  leaves  much  narrowed  below  the 
middle,  sessile  and  connate  around  the  stem.  Flowers  axillary,  sessile, 
solitary  or  clustered.  Calyx  with  5  linear-lanceolate  lobes,  its  tube 
ovoid.  Corolla  but  little  longer  than  the  calyx,  5-lobed,  its  tube  cam- 
panulate  or  tubular,  swollen  at  the  base.  Stamens  5,  inserted  on  the 
corolla  tube.  Ovary  generally  3-celled  with  i  ovule  in  each  cavity. 
Style  slender ;  stigma  3-5-lobed.  Fruit  an  orange  or  red  drupe,  con- 
taining bony  nutlets. 

1.  Triosteum  perfoliatum,  L.     (L.,  per,  through ;  folium,  leaf.)     FEVER-WORT 
or  HORSE-GENTIAN.     Stems  stout,  2  to  4  feet  high,  beset  with  soft  hairs.     Leaves 
oval,  abruptly  constricted  below  the  middle,  4  to  9  inches  long.     Flowers  brownish 
purple,  clustered  in  the  axils  of  the  leaves.     Drupes  orange-color.     In  rich  soil. 

2.  Triosteum  angustif61ium,  L.     (L.,  angustus,  narrow;  folium,  leaf.)     YEL- 
LOW or  NARROW-LEAVED  HORSE-GENTIAN.    Stems  more  slender  than  in  the 
preceding  species,  bristly  hairy,  i  to  3  feet  tall.     Leaves  lanceolate,  tapering  below 
the  middle,  3  to  5  inches  long.     Flowers  pale  greenish  yellow,  usually  solitary  in  the 
axils.     In  shady  situations. 


1 14  Introduction  to  Botany. 

IV.  LONICERA.    Honeysuckle  or  Woodbine. 

(Latinized  form  of  Lonitzer,  German  herbalist.) 

Erect  or  climbing  shrubs,  with  opposite,  entire,  sometimes  perfoliate 
leaves.  Flowers  in  clusters,  or  sometimes  solitary.  Calyx  nearly 
globular,  slightly  5-toothed.  Corolla  tubular  or  funnel-form,  more  or 
less  irregularly  5-lobed.  Stamens  5,  inserted  on  the  tube  of  the  corolla. 
Ovary  2-3-celled,  with  numerous  ovules  in  each  cavity.  Style  slender 
and  stigma  capitate  ;  berry  fleshy. 

1.  Lonicera  Sullivantii,   Gray.     (Latin  genitive  of  proper  name.)      SULLI- 
VANT'S  HONEYSUCKLE.    Smooth  and  glaucus,  3  to  6  feet  long.     Leaves  oval  or 
obovate,  glaucus,  and  often  pubescent  beneath.    Corolla  pale  yellow,  hairy  within, 
its  tube  about  |  inch  long.     Filaments  nearly  glabrous.     In  woods. 

2.  Lonicera  sempervirens,  L.     (L.,  semper,  always;  virens,  growing  green.) 
TRUMPET  or  CORAL  HONEYSUCKLE.    Climbing  high.    Leaves  oval,  the  upper- 
most connate-perfoliate,  dark  green  above,  glaucus  beneath.     Flowers  in  whorls  in 
terminal,  interrupted  spikes.     Corolla  scarlet  outside,  yellow  inside,  and  sometimes 
yellow  throughout,  from  i  to  1$  inches  long,  trumpet-shaped.     Berries  scarlet. 
Common  in  cultivation.     In  copses,  or  habitat  various. 

VALERIANACEJE.    VALERIAN  FAMILY. 

Herbs,  with  opposite,  exstipulate  leaves,  and  small,  more  or  less 
irregular  flowers  in  forked  or  panicled  cymes.  Calyx  tube  adherent  to 
the  ovary,  its  limb  nearly  or  quite  wanting,  often  becoming  prominent  in 
the  fruit.  Corolla  tubular  or  funnel-form,  mostly  5-lobed,  and  sometimes 
irregular.  Stamens  1-4,  inserted  on  the  tube  of  the  corolla  alternate 
with  its  lobes,  mostly  exserted.  Ovary  inferior,  i-3-celled  ;  i  cell  con- 
taining a  single  ovule  and  the  others  empty.  Style  slender ;  stigmas 
1-3.  Fruit  dry  and  indehiscent. 

I.  VALERIAN  A.    Valerian. 

(Latin  name  of  unknown  origin.) 

Perennial,  mostly  tall  herbs  with  thickened,  strong-scented  roots, 
and  paniculate,  cymose  flowers.  Limb  of  the  calyx  divided  into  several 
plumose  bristles  which  are  inrolled  in  the  flower,  but  straighten  out  and 
become  conspicuous  in  the  fruit.  The  funnel-form  or  tubular  corolla 
gibbous  near  the  base  and  nearly  regularly  5-lobed  above.  Stamens 
mostly  3.  Fruit  i -celled  and  seedlike. 

i.   Valeriana pauciflbra, Michx.    (L.,paucus,  few;  flos,fioris,  flower.)    LARGE- 


Dicotyledones.  115 

FLOWERED  VALERIAN.  Stem  smooth,  erect  or  ascending,  i  to  3  feet  high.  Base 
leaves  cordate  or  ovate,  stem  leaves  with  3-7  ovate  leaflets.  Divisions  of  the  pani- 
cled  cyme  few-flowered.  Corolla  pale  pink,  its  tube  £  inch  or  more  long.  In 
moist  soil. 

2.  Valeriana  edulis,  Nutt.  (L.,  edulis,  edible.)  EDIBLE  VALERIAN.  Smooth 
or  finely  pubescent,  erect,  i  to  4  feet  high  from  a  deep,  fusiform  root.  Basal  leaves 
spatulate  to  lanceolate.  Stem  leaves  pinnately  3~7-parted  into  linear  or  lanceolate 
segments.  Inflorescence  an  elongate,  interrupted  panicle.  Flowers  small,  yellow- 
ish white,  nearly  dioecious.  On  moist  prairies. 

II.  VALERIANELLA.    Corn  Salad  or  Lamb-lettuce. 

(Name  a  diminutive  of  Valerian.) 

Annuals  or  biennials,  mostly  glabrous,  and  dichotorhously  branched. 
Leaves  tender  and  succulent,  those  of  the  base  tufted,  entire ;  the  stem 
leaves  often  dentate.  Limb  of  the  calyx  obsolete  or  short  and  toothed. 
Corolla  funnel-form  or  tubular,  equally  or  unequally  5-lobed,  small,  and 
white  or  whitish.  Stamens  3.  Style  slightly  3-lobed.  Fruit  3-celled, 
2  cells  empty  and  the  third  containing  a  single  seed.  Inflorescence  a 
corymbed  or  panicled  cyme. 

1.  Valerianella  chenopodifolia,  DC.      (Gr.,  chen,  goose;  pou,  foot;  folium, 
leaf.)     GOOSE-FOOT  CORN  SALAD.     Smooth,  i  to  2  feet  high.    Lower  leaves 
broadly  spatulate,  somewhat  repand,  stem  leaves  oblong-oval  to  lanceolate.    Cymes 
£  inch  or  more  broad.     Flowers  very  small,  white;  fruit  triangular-pyramidal  in 
form.     In  moist  soil. 

2.  Valerianella  radiata,  Dufr.     (L.,  radiatus,  provided  with  spokes  or  rays.) 
BEAKED  CORN  SALAD.     Nearly  or  quite  glabrous,  6  to  18  inches  high.     Lower 
leaves  spatulate  or  oblong-oval,  entire ;  upper  leaves  oblong-elliptic  to  lanceolate, 
often  dentate.     Cymes  about  5  inch  broad  or  less.     Flowers  white  and  very  small. 
Fruit  tetragonal,  broadly  grooved,  oblong  or  ovoid,  mostly  downy  pubescent.     In 
moist  soil. 

3.  Valerianella    stenocarpa,    Krok.       (Gr.    stenos,    narrow';    karpos,    fruit.) 
NARROW-CELLED   CORN  SALAD.     Similar  in  general  aspect  to  the  preceding 
species,  but  the  fruit  commonly  glabrous,  sometimes  downy-pubescent,  and  the 
grooves  narrow.     In  moist  soil. 

CAMPANULACEJE.    BELLFLOWER  FAMILY. 

Herbs,  mostly  with  a  milky  juice,  alternate,  exstipulate  leaves,  and 
solitary  or  scattered  flowers.  Calyx  tube  adherent  to  the  ovary,  its 
limb  mostly  5-lobed  or  parted.  Corolla  gamopetalous,  5-lobed,  its  tube 
sometimes  parted  down  one  side.  Stamens  5,  inserted  with  the  corolla 
and  alternate  with  its  lobes.  Ovary  generally  2-5-celled  with  axillary 
placenta? ;  or  sometimes  i -celled  with  2  parietal  placentae.  Style  simple 


n6  Introduction  to   Botany. 

with  a  tuft  of  hairs  above  ;  stigma  generally  2-5-lobed.     Fruit  a  capsule 
or  berry  with  many  small  seeds. 

I.  SPECULARIA.    Venus's  Looking-glass. 

(L.,  Specularia,  a  window  glass  made  of  talc;   from  bluish  color  of  the  flowers.) 

Low  annuals,  with  alternate  leaves  and  axillary  blue  or  purplish 
flowers ;  the  earlier  flowers  small  and  cleistogamous.  Calyx  5-,  or 
sometimes  3~4-lobed.  Corolla  wheel-shaped,  5-lobed.  Stamens  5, 
with  membranous,  hairy  filaments.  Ovary  mostly  3-celled  ;  sometimes 
2-  or  4-celled.  Stigma  usually  3-lobed.  Capsule  opening  by  lateral 
valves. 

1.  Specularia  perfoliata,  A.  DC.     (L.,  per,  through;  folium,  leaf.)     Some- 
what pubescent,  6  to  20  inches  tall.     Leaves  rounded,  crenate-dentate,  cordate  and 
clasping  at  the  base.     Flowers  solitary,  or  few  together  in  the  axils,  sessile.     The 
upper  and  older  flowers  with  an  expanded  and  conspicuous  corolla,  blue  or  violet. 
In  open  grounds  or  dry  woods. 

2.  Specularia  leptocarpa,  Gray.     (Gr.  leptos,  small;  karpos,  fruit.)     Simple  or 
branched,  6  to  15  inches  high.    Leaves  lanceolate,  with  mostly  solitary  sessile  flowers 
in  the  axils.    Calyx  lobes  4-5,  awl-shaped,  but  in  the  earlier  flowers  only  3.     Corolla 
of  the  earlier  flowers  rudimentary,  of  the  later  flowers  rotate,  3  inch  or  more  broad. 
Capsule  nearly  cylindrical.     In  dry  soil. 

COMPO'SITJE.    COMPOSITE  FAMILY. 

Flowers  in  a  compact  head,  borne  on  an  enlarged  common  receptacle, 
the  head  having  the  appearance  of  a  double  flower.  Many  bracts  sub- 
tend the  head,  forming  an  involucre  somewhat  simulating  a  calyx. 
Limb  of  the  calyx  (termed  pappus  in  this  family),  rising  from  near  the 
summit  of  the  I -celled  ovary  in  the  form  of  bristles,  awns,  scales,  or 
teeth,  or  in  the  form  of  a  cup,  or  sometimes  entirely  absent.  Corolla 
strap-shaped,  or  tubular,  mostly  5-lobed.  Stamens  5,  rarely  4,  inserted 
on  the  tube  of  the  corolla ;  anthers  united  into  a  tube  around  the  style. 
Ovary  i-celled  and  i-seeded;  style  2-cleft.  Fruit  a  dry,  i-seeded 
achene.  Heads  which  are  composed  of  strap-shaped  (ligulate)  corollas 
throughout,  or  only  at  the  margin,  are  termed  radiate,  flowers  with  ligu- 
late  corollas  being  termed  ray  flowers.  Heads  without  ray  flowers  are 
termed  discoid.  The  family  is  divided  into  two  series  or  suborders  : 
I.  TubuliflorcB)  in  which  the  corollas  are  all  tubular;  or  ligulate  only  at 
the  margin  of  the  head,  where  they  are  pistillate,  or  neutral.  II.  Ligitti- 
flora,  in  which  the  corollas  are  ligulate  in  all  flowers  of  the  head,  and  all 
of  the  flowers  are  perfect.  Frequently  bracts,  in  this  family  called  chaff, 


Dicotyledones.  117 

occur  on  the  receptacle  among  the  flowers.      The  receptacle  is  said 
to  be  naked  when  these  are  absent. 

A.  Corollas  all  tubular,  or  ligulate  and  pistillate,  or  neutral  only,  at  the  margin  of  the  head. 

Flowers  of  the  head  all  tubular;  dioecious.  ANTENNARIA  II. 

Disk  flowers  tubular;   ray  flowers  ligulate. 

Ray  flowers  white,  pink,  or  purple,  rarely  yellow. 
Pappus  of  capillary  bristles. 

Ray  flowers  numerous  and  pistillate;  bracts  of  the  involucre  little  im- 
bricated;  receptacle  naked.  ERIGERON  I. 
Pappus  a  minute  crown  or  wanting. 

(a)   Ray  flowers  pistillate  or  neutral ;  bracts  of  the  involucre  imbricated  in 

several  rows;  receptacle  convex  and  chaffy  near  the  summit;  heads 

on  long,  terminal  peduncles.  ANTHEMIS  III. 

(6)  Ray  flowers  pistillate;  bracts  of  the  involucre  imbricated  in  few  rows, 

appressed;  receptacle  chaffy;  heads  small  in  corymbose  clusters. 

ACHILLEA  IV. 

(c~)  Ray  flowers  pistillate;  disk  flowers  with  flattened  tubes;  involucral 
scales  imbricated  in  several  rows;  receptacle  without  chaff;  heads 
large  on  long  peduncles.  CHRYSANTHEMUM  V. 

Ray  flowers  yellow. 

Pappus  of  capillary  bristles;  disk  flowers  as  well  as  ray  flowers,  when  present, 
yellow.  SENECIO  VI. 

B.  Corollas  all  ligulate,  and  all  flowers  of  the  head  perfect. 

Heads  borne  singly  on  a  scape. 

(a)    Leaves  tufted  at  the  base,  entire.  TROXIMON  VII. 

(b)    Leaves  tufted  at  the  base,  pinnatifid  or  runcinate.  TARAXACUM  VIII. 

Heads  borne  on  long,  bracted  peduncles,  sometimes  scapose.  PYRRHOPAPPUS  IX. 

Heads   in   corymbose   or  paniculate   clusters   on   leafy   stems;    leaves  with   prickly 

margins.  SONCHUS  X. 

I.    Tubuliflora. 

I.  ERIGERON.    Fleabane. 

(Gr.,  eri,  early;  geron,  old  man,  from  the  hoariness  of  some  of  the  early  spring  species.) 

Heads  radiate  on  the  margin.  Ray  flowers  white,  pinkish,  or  purple  ; 
disk  flowers  yellow.  Ray  flowers  numerous  and  pistillate.  Involucre 
hemispheric  or  campanulate,  its  bracts  narrow  and  little,  or  not  at  all, 
imbricated.  Receptacle  naked,  nearly  flat.  Pappus  a  row  of  capil- 
lary bristles  with  smaller  ones  interspersed.  Achenes  flattened,  often 
pubescent  and  2-nerved. 

i.  Erigeron  annuus,  Pers.  (L.,  annuus,  annual.)  SWEET  SCABIOUS.  Slightly 
pubescent  annuals,  i  to  4  feet  high,  corymbosely  branched  above.  Lower  leaves 
petioled,  ovate,  or  ovate-lanceolate,  mostly  coarsely  dentate;  the  upper  leaves 
lanceolate  or  ovate-lanceolate,  sessile  or  short-petioled,  sharply  dentate.  40-70 
linear,  white  or  purplish,  rays.  Pappus  doubled  by  an  outer  row  of  slender 
scales;  the  inner  row  of  capillary  bristles  often  wanting  in  the  ray  flowers.  In 
fields  and  waste  places. 


n8  Introduction  to  Botany. 

2.  Erigeron  strigosus,  Muhl.     (L.,  strigosus,  thin  or  narrow.)     DAISY  FLEA- 
BANE.     Resembling  the  preceding  species,  but  smaller,  and  the  lower  leaves  oblong 
or  spatulate,  and  tapering  into  a  slender  petiole;    upper   leaves  linear-oblong  or 
linear-lanceolate.    Clothed  with  an  appressed  pubescence.     Rays  white,  and  twice 
the  length  of  the  puberulent  involucre.     In  fields. 

3.  Erigeron  bellidifolius,  Muhl.     (L.,  bellis,  bellidis,  the  ox-eye  daisy;  folium, 
leaf.)     ROBIN'S  PLANTAIN.    Hairy  perennial,  producing  stolons  or  offsets  at  the 
base.      Basal  leaves  tufted,  obovate,  or  spatulate ;   upper  leaves  few  and  distant, 
anceolate-oblong,  partly  clasping.      Heads  i  to  15  inches  broad  on  slender  pedun- 
cles.   Rays  about  50,  violet  or  purple.     Pappus  simple.     Moist  banks  and  copses. 

4.  Erigeron  Philadelphicus,  L.    COMMON  FLEABANE.    Hairy  or  nearly  gla- 
brous perennial,  forming  stolons  or  offsets  at  the  base.     Stems  slender,  i  to  3  feet 
high.    Lower  leaves  obovate  or  spatulate,  dentate,  tapering  to  a  short  petiole. 
Upper  leaves  oblong  or  lanceolate,  clasping  at  the  base.     Rays  100  or  more,  light 
rose-purple.     Pappus  simple.     In  fields  and  woods. 

II.  ANTENNARIA.    Everlasting. 

(Named  from  resemblance  of  the  pappus  to  the  antennae  of  some  insects.) 

Flowers  of  the  head  many,  dioecious,  all  tubular.  Corolla  of  the 
staminate  flowers  truncate  and  minutely  dentate,  the  anthers  caudate, 
pappus  scant,  club-shaped,  barbed,  or  smooth  above.  Pistillate  flowers 
with  slender,  tubular  corolla  and  copious,  capillary  pappus,  united 
beneath  to  form  a  ring.  Involucre  white  or  colored,  and  dry,  the 
scales  numerous  and  imbricated.  Receptacle  without  chaff,  and  con- 
vex or  flat.  Perennial  herbs  clothed  with  a  white  wool.  Leaves 
entire. 

i.  Antennaria  plantaginifolia,  Richards.  (L., plantago •,  plantain  ;  folium,  leaf.) 
PLANTAIN  LEAF  or  MOUSE-EAR  EVERLASTING.  3  to  18  inches  high,  spreading 
by  stolons.  Young  leaves  softly  woolly,  becoming  green  above  and  hoary  beneath. 
Basal  leaves  petioled,  obovate,  or  broadly  spatulate,  3-nerved.  Stem  leaves  lanceo- 
late, appressed.  Heads  in  corymbose  clusters.  Scales  of  the  involucre  white  or 
greenish  white,  imbricated  in  about  3  rows.  In  dry  soil  or  open  woods. 

III.   ANTHEMIS.    Chamomile. 

(The  ancient  Greek  name  of  the  chamomile.) 

Heads  radiate  on  the  margins ;  ray  flowers  white  or  yellow,  either 
pistillate  or  neutral.  Disk  flowers  yellow,  perfect.  Involucre  hemi- 
spheric, with  bracts  imbricated  in  several  rows.  Receptacle  convex 
and  chaffy,  at  least  near  the  summit.  Pappus  a  minute  crown  or 
wanting.  Achenes  oblong  and  ribbed.  Strong-scented  annual  or 
perennial  herbs,  with  alternate,  pinnatifid,  or  dissected  leaves  and 
heads  usually  borne  on  long  terminal  peduncles. 


Dicotyledones.  119 

i.  Anthemis  Cdtula,  L.  (Gr.,  kotyle,  a  small  measure  or  cup.)  MAYWEED 
or  DOG  FENNEL.  Strong-scented  and  pungent  annual,  branched,  i  to  2  feet  high. 
Leaves  finely  1-3  pinnately  dissected.  Rays  white,  10-18,  neutral  or  with  an  abor- 
tive pistil.  Pappus  none.  Receptacle  with  bristly  chaff  near  the  summit  only. 
By  roadsides  or  in  fields  and  waste  places. 

IV.  ACHILLEA.    Yarrow. 

(Named  for  Achilles,  who  is  supposed  to  have  discovered  its  virtues.) 

Heads  small,  with  both  radiate  and  tubular  flowers,  in  corymbose 
clusters  at  the  ends  of  the  branches.  Ray  flowers  white,  few  and 
fertile.  Disk  flowers  yellow.  Bracts  of  the  involucre  imbricated  in 
a  few  rows,  appressed.  Receptacle  chaffy,  convex,  or  flattish.  Pappus 
none.  Achenes  flattened  and  somewhat  margined.  Perennial  herbs, 
with  serrate,  pinnatifid,  or  finely  dissected,  alternate  leaves. 

i.  Achillea  Millefolium,  L.  (L.,  mille,  thousand;  folium,  leaf.)  COMMON 
YARROW  or  MILFOIL.  Perennial,  from  a  horizontal  rootstock,  becoming  i  to  2 
feet  high.  Leaves  twice  pinnatifid  into  slender  segments.  Flowers  in  a  compound, 
flat-topped  corymb.  Heads  small  and  numerous;  ray  flowers  4-5,  mostly  white, 
sometimes  pink  or  purple ;  bracts  of  the  involucre  oblong,  acute.  Habitat  various. 

V.  CHRYSANTHEMUM.    Ox-eye  Daisy. 

(Gr.,  chrysanthemon,  golden  flower.) 

Heads  composed  of  both  tubular  and  ray  flowers;  the  rays  fertile, 
white,  rose-colored,  or  yellow.  Disk  flowers  with  flattened  tubes,  per- 
fect. Scales  of  the  involucre  imbricated  in  several  rows.  Receptacle 
flat  or  convex,  without  chaff.  Biennial,  perennial,  or  annual  herbs, 
with  mostly  large  heads  borne  on  long  peduncles. 

i.  Chrysanthemum  Leucanthemum,  L.  (Gr.,  leukos,  white ;  anthemon,  flower.) 
OX-EYE  or  WHITE  DAISY.  Perennial,  i  to  3  feet  high.  Branches  terminated  by 
a  single  large  head  on  a  long  peduncle.  Rays  white,  20-30.  Pappus  none.  Basal 
leaves  petioled,  spatulate,  incised.  Upper  leaves  spatulate  to  linear,  cut-toothed, 
clasping  at  the  base.  Scales  of  the  involucre  with  scarious  and  brown  margins. 
In  pastures,  fields,  and  waste  places. 

VI.   SENECIO.    Groundsel. 
(L.,  senex,  old  imn,  from  the  hoariness  of  some  species.) 

Heads  usually  consisting  of  both  disk  and  ray  flowers.  Ray  flowers, 
when  present,  pistillate  ;  disk  flowers  perfect  and  fertile.  Both  disk  and 
ray  flowers  usually  yellow.  Pappus  of  numerous  fine  capillary  bristles. 


I2O  Introduction  to  Botany. 

Involucre  of  i  row  of  bracts,  subtended  by  a  few  bractlets.  Receptacle 
flat  and  naked.  Annual  or  perennial  herbs,  with  solitary  or  corymbed 
heads.  Achenes  mostly  cylindrical,  5-io-ribbed,  downy. 

1.  Senecio  lobatus,  Pers.    (Gr.,  lobos,  lobe.)    BUTTERWEED  or  CRESS-LEAVED 
GROUNDSEL.     Glabrous  or  only  slightly  woolly  annual,  i  to  3  feet  high.    Leaves 
pinnately  divided,  the  lower   ones   petioled.      Heads    rather    more    than   £   inch 
broad,  numerous  in  terminal  corymbs.    Rays  6-10,  conspicuous.     Involucre  nearly 
cylindric,  usually  with  no  smaller  outer  bracts.     In  wet  grounds. 

2.  Senecio  aureus,  L.     (L.,  aureus,  golden  yellow.)     GOLDEN  RAGWORT  or 
SQUAW  WEED.     Nearly  or  quite  glabrous  perennial,   i  to  2^  feet  high.     Basal 
leaves  long-petioled,  rounded  or  nearly  heart-shaped,  crenate.     Stem  leaves  vary- 
ing from  lyrate  below  to  lanceolate  above,  and  more  or  less  pinnatifid,  sessile, 
and  clasping.     Heads  §  of  an  inch  or  more  broad,  borne  on  slender  peduncles  in 
an  open  corymb.    Rays  8-12,  yellow.    This  species  is  quite  variable.    Var.  obovatus, 
T.  &  G.,  has  basal  leaves  round-obovate,  the  earliest  being  almost  sessile  and  tufted. 
Var.  Balsamitce,  T.  &  G.,  has  spatulate,  oblong,  or  lanceolate  basal  leaves,  lyrate, 
pinnatifid  upper  leaves,  and  heads  small  and  numerous.     In  moist,  open  ground. 


II.   Liguliflora. 

VII.   TROXIMON. 

Perennial  or  annual  herbs,  with  leaves  tufted  at  the  base,  linear  or 
lanceolate  and  entire.  Heads  of  ligulate  flowers  large,  yellow  or  rarely 
purple,  borne  singly  at  the  end  of  a  naked  or  sometimes  bracted  scape. 
Scales  of  the  involucre  imbricated  in  2-3  rows.  Receptacle  flat,  naked, 
or  pitted.  Achenes  beaked,  or  sometimes  beakless,  lo-ribbed.  Pappus 
of  many  rigid  capillary  bristles. 

1.  Troximon  cuspidatum,   Pursh.     (L.,   cuspidatus,  pointed.)     Scape   i   foot 
high.     Leaves   lanceolate,  elongate,  and  tapering,  entire,  woolly  on  the  margins. 
Achenes  beakless.     Plains. 

2.  Troximon  glaucum,  Nutt.     (Gr.,  glaukos,  bluish  gray.)     Scape  i  to  2  feet 
high.     Leaves  oblong  or  lanceolate,  entire,  or  sometimes  dentate  or  pinnatifid. 
Heads  i  to  2  inches  wide.    Achenes  prominently  beaked.    Plains. 

VIII.  TARAXACUM.    Dandelion. 

(Gr.,  tarasso,  to  disquiet,  in  allusion  to  medicinal  properties.) 

Perennial  or  biennial  herbs  from  a  thickened  tap-root.  Heads  large, 
many-flowered,  solitary  on  the  summit  of  a  slender,  hollow  scape,  which 
exudes  a  milky  secretion  when  broken.  Sca]es  of  the  involucre  in  2 
rows,  the  outer  scales  short,  reflexed  with  age,  those  of  the  inner  row 


Dicotyledones.  121 

linear  and  erect.     Achenes  4-5 -ribbed,  prolonged  into  a  beak  bearing 
a  copious,  soft,  capillary  pappus.     Flowers  yellow. 

i.  Taraxacum  officinale,  Weber.  (L.,  officina,  workshop.)  COMMON  DAN- 
DELION. Leaves  pinnatifid  or  runcinate,  clustered  near  the  ground.  Heads 
crowded  with  many  golden  yellow  flowers.  Beak  bearing  the  pappus  becoming 
very  elongate  and  filiform  in  fruit.  In  pastures,  fields,  and  yards. 

IX.  PYRRHOPAPPUS.    False  Dandelion. 

(Gr.,  pyrrhos,  reddish  or  flame-colored;  pappos,  pappus.) 

Mostly  perennial  herbs,  with  the  general  characteristics  of  the  dan- 
delion. Large  heads  of  yellow  flowers  borne 'on  long  and  usually 
bracted  peduncles.  Pappus  of  a  reddish  color,  surrounded  at  the  base 
by  a  soft,  hairy  ring,  and  borne  above  the  achene  on  an  elongate  beak. 

1.  Pyrrhopappus  Carolinianus,  DC.    Stems  branching,  i  to  2  feet  high.    Basal 
leaves  oblong  or  lanceolate,  entire,  toothed,  or  pinnatifid.     Upper  leaves  nearly 
lanceolate   and   partly   clasping.  .Outer  bracts  of  the  involucre   awl-shaped  and 
spreading,  inner  bracts  erect  and  indurated  at  the  apex.     Beak  much  longer  than 
the  achene.     In  dry  fields. 

2.  Pyrrhopappus  scaposus.  (Gr.,  skapos,  a  staff.)  ROUGH  FALSE  DANDELION. 
Perennial  from  tuberous  thickened  roots.     No  stem  leaves  present.     Basal  leaves 
deeply  pinnatifid.    Scape  often  naked,  or  with  a  small  basal  leaf.     On  prairies. 

X.  SONCHUS.    Sow  Thistle. 

(The  ancient  Greek  name.) 

Coarse  annual  or  perennial  herbs,  exuding  a  milky  secretion  when 
wounded.  Leaves  mostly  lobed  or  pinnatifid,  with  prickly,  toothed 
margins.  Heads  of  yellow  flowers  in  corymbose  or  paniculate  clusters. 
Bracts  of  the  involucre  imbricated  in  several  rows,  becoming  shorter 
toward  the  outside.  Achenes  somewhat  flattened,  io-2o-ribbed.  Pappus 
of  many  soft  and  fine  bristles,  not  borne  on  an  elongated  beak. 

1.  Sonchus  oleraceus,  L.     (L.,  oleraceus,  pertaining  to  vegetables.)    COMMON 
Sow  THISTLE  or  HARE'S  LETTUCE.    Annual,  i  to  5  feet  high.    Basal  leaves 
petioled,  lyrate-pinnatifid   in   outline.     Upper   leaves  sessile  and  clasping  by  an 
auricled  or  sagittate  base,   margins  with   mucronate  teeth.     Achenes  sfriate  and 
transversely  wrinkled.     Flowers  pale  yellow.     In  fields  and  waste  places. 

2.  Sonchus  asper,  Vill.    (L.,  asper,  rough.)    SPINY-LEAVED  Sow  THISTLE. 
Similar  in  general  aspect  to  the  preceding  species.    Lower  leaves  petioled,  obovate, 
or  spatulate.     Upper  leaves  sessile  and  clasping,  with  rounded  basal  lobes;   the 
margins   more   rigidly  spiny-toothed    than   in   the   preceding   species.      Achenes 
flattened  and  margined,  3-nerved  on  each  side.     In  fields  and  waste  places. 


INDEX   TO    FLORA. 


Acanthaceae,  108. 

Barberry,  43. 

Butterfly  weed,  92. 

Acanthus  family,  108. 

Barberry  family,  42. 

Butternut,  28. 

Acer,  74. 

Barren  strawberry,  61. 

Butterweed,  120. 

Achillea,  119. 

Basswood,  78. 

Actaea,  39. 

Bastard  toadflax,  34,  35. 

Callirrhoe,  79. 

^Esculus,  75. 

Beardtongue,  103. 

Calycocarpum,  44. 

Ague  tree,  45. 

Bedstraw,  111. 

Cainassia,  21. 

Alllum,  20. 

Bellflower  family,  115. 

Camelina,  52. 

Alyssum,  53,  54. 

Berberidaceae,  42. 

Campanulaceae,  115. 

Amaryllidaceae,  24. 

Berberis,  43. 

Campion,  37. 

Amelanchier,  63. 

Betula,  30. 

Cancer  root,  107. 

American  Black  Larch,  14. 

Bignonia,  107,  108. 

Candle  tree,  108. 

American  cowslip,  90. 

Bignoniaceae,  107. 

Caprifoliaceae,  "112. 

American  ivy,  77. 

Bignonia  family,  107. 

Capsella,  52. 

American  pea  vine,  68.          « 

Bilberry,  87. 

Cardamine,  50. 

Amorpha,  67. 

Bindweed,  93,  94. 

Carex,  17. 

Ampelopsis,  77. 

Birch,  30,  31. 

Carpinus,  31. 

Anacardiaceae,  73. 

Bitter  cress,  50. 

Carrot  family,  82. 

Anagallis,  89. 

Bittersweet,  102. 

Carya,  28. 

Androsace,  89. 

Blackberry,  59. 

Caryophyllaceae,  37. 

Anemone,  40. 

Black  haw,  113. 

Castilleia,  104,  105. 

Angiospermae,  15. 

Black  mustard,  49. 

Catalpa,  108. 

Anonaceae,  38. 

Black  snakeroot,  84. 

Catchfly,  37. 

Anteunaria,  118. 

Bladder  nut,  74,  75. 

Cat  mint,  100. 

Anthemis,  118,  119. 

Bladderwort,  106. 

Cat-tail,  15. 

Aphyllon,  106,  107. 

Bladderwort  family,  105. 

Caulophyllum,  48. 

Apple,  63. 

Bloodroot,  45,  46. 

Ceanothus,  76. 

Apple  of  Sodom,  102. 

Blueberry,  87,  88. 

Cedar,  white,  14  ;  red,  14. 

Aquilegia,  39. 

Blue  birch,  31. 

Celandine  poppy,  46. 

Arabia,  53. 

Blue  cohosh,  43. 

Celtis,  34. 

Araceae,  18. 

Blue-eyed  grass,  26. 

Centunculus,  89. 

Arbor  vitae,  14. 

Blue  grass,  16. 

Cerastium,  37. 

Argemone,  45. 

Bluets,  110,  111. 

Cercis,  68. 

Arisaema,    18  ;    inflorescence 

Borage  family,  96. 

Chaerophyllum,  85. 

of,  18. 

Boraginaceae,  96. 

Chatfweed,  89. 

Arrow-wood,  113. 

Box  elder,  74. 

Chamomile,  118. 

Arum  family,  18. 

Box-thorn,  102. 

Cherry,  57,  58. 

Asclepiadaceae,  91. 

Bramble,  59. 

Chervil,  85. 

Asclepias,  92. 

Brassica,  49. 

Chickweed,  37,  38. 

Asclepiodora,  92. 

Broom-rape  family,  106. 

Chinese  primrose,  88. 

Ash,  91. 

Bryophyta,  5. 

Chrysanthemum,  119. 

Asimina,  88. 

Buckeye,  75. 

Cinquefoil,  60,  61. 

Astragalus,  67,  68. 

Buckthorn,  75,  76. 

Claytonia,  36. 

Avens,  61,  62. 

Buckthorn  family,  75. 

Cleavers,  111,  112. 

Buckwheat  family,  35. 

Clover,  66. 

Baneberrv,  89- 

Bulbous  cress,  50. 

Cohosh,  39. 

Baptisia,  65. 

Buttercup,  41,  42. 

Columbine,  39,  40. 

I23 

I24 


introduction  to  Botany. 


Comandra,  84,  35. 

Dutchman's  breeches,  46. 

Gold-of-pleasure,  52. 

Commelinaceae,  19. 

Dwarf  alder,  76. 

Gooseberry,  55. 

Composite,  116. 

Goosegrass,  112. 

Composite  family,  116. 

Easter  bell,  22. 

Gramineae,  15. 

Conifene,  12. 

Ebenaceae,  90. 

Grape  family,  76. 

Conopholis,  10T. 
Convolvulaceae,  92. 

Ebony  family,  90. 
Elder,  112. 

Grape,  77. 
Grass  family,  15. 

Convolvulus,  93,  94. 

Eleocharis,  17. 

Grasp  flower,  diagram  of,  16. 

Cornaceaa,  86. 

Ellisia,  96. 

Greater  henbit,  101. 

Cornel,  86. 

Elm,  33. 

Greenbrier,  20. 

Corn  salad,  115. 

Epigaea,  87. 

Green  dragon,  18. 

Cornus,  86. 

Ericaceae  86. 

Green  milkweed,  92. 

Corydalis,  4T. 
Corylus,  32. 
Cottonwood,  29. 
Cow  parsnip,  83. 
Cowslip,  88. 
Crab  apple,  63. 
Cranberry,  87. 
Cranberry  tree,  113. 

Erigenia,'s5,  86. 
Erigeron,  117,  118. 
Erythronium,  22. 
Euphorbia,  72. 
Euphorbiaceae,  72. 
Evening  primrose,  82. 
Evening  primrose  family,  81. 

Gromwell,  97. 
Ground  ivy,  100. 
Ground  laurel,  87. 
Ground  pink,  95. 
Ground  plum,  67,  68. 
Groundsel,  119. 
Gymnocladus,  69. 
Gymnospermse,  12. 

Cranesbill,  TO. 

Cratsegus,  64. 
Cress,  49,  50. 

False  acacia,  67. 
False  dandelion,  121. 

Hackberry,  34. 
Hackmatack,  14. 

Cross  vine,  107,  108. 
Crowfoot,  41,  42. 

False  flax,  52. 
False  grape,  77. 

Harbinger  of  spring,  85,  86. 
Hare's  lettuce,  122. 

Crowfoot  family,  38. 

False  gromwell,  97,  98. 

Haw,  &4. 

Cruciferae,  47. 

False  indigo,  65,  67. 

Hawthorn,  64. 

Cupseed,  44. 

False  pimpernel,  89. 

Hazelnut,  32. 

Cupuliferae,  30. 

False  rue  anemone,  39. 

Heart's-ease,  79,  81. 

Currant,  55,  56. 

False  Solomon's  seal,  23,  24. 

Heath  family,  86. 

Custard-apple  family,  88. 
Cynoglossum,  96,  97. 

Fever-wort,  113. 
Figwort  family,  103. 

Hedge  mustard,  49. 
Henbit,  101. 

Cyperaceae,  18. 

Filbert,  32. 

Hepatica,  41. 

Cyperus,  17. 

Fire  pink,  37. 

Heracleum,  83. 

Cypripedium,  26. 

Five-finger,  60,  61. 

Hickory,  28. 

Fleabane,  117,  118. 

Honey  locust,  69. 

Daisy,  119. 

Flower-de-luce,  25. 

Honeysuckle,  114. 

Dandelion,  120. 
Date  plum,  90. 

Four  o'clock  family,  36. 
Foxglove  beardtongue,  103. 

Honeysuckle  family,  112. 
Hop  hornbeam,  31,  32. 

Dead  nettle,  100,  101. 

Fragaria,  60. 

Hornbeam,  31. 

Delphinium,  40. 

Fraxinus,  91. 

Horse-chestnut,  75. 

Dentaria,  61. 
Desmanthus,  70. 

Fumariaceae,  46. 
Fumitory  family,  46. 

Horse-gentian,  113. 
Horse  nettle,  102. 

Dewberry,  59. 

Hound's  tongue,  96,  97. 

Dianthera,  109. 

Galanthus,  25. 

Houstonia,  110,  111. 

Dicentra,  46. 

Galium,  111,  112. 

Huckleberry,  87. 

Dicotyledones,  27. 

Gama  grass,  16. 

Hydrophyllaceae,  95. 

Diospyros,  90. 

Garlic,  20. 

Hydrophyllum,  95,  96. 

Dock,  35. 

Gaylussacia,  87. 

Hypoxis,  24. 

Dodecatheon,  90. 

Geraniaceae,  70. 

Dog-fennel,  119. 

Geranium,  70. 

Indian  bean,  108. 

Dogtooth  violet,  22. 

Geranium  family,  70. 

Indian  paint-brush,  105. 

Dogwood,  86. 

Geum,  61,  62. 

Indian  turnip,  18. 

Dogwood  family,  86. 

Gill-over-the-ground,  100. 

Innocence,  110,  111. 

Draba,  53. 

Gleditschia,  69. 

Ipomoea,  93. 

Dragon  arum,  18. 

Goat's  beard,  58. 

Iridaceae,  25. 

Dry  strawberry,  61. 

Golden  ragwort,  120. 

Iris,  25. 

Index  to  Flora. 


125 


Ironwood,  31. 

Menispermaceae,  44. 

Parsley,  84. 

Isopyrum,  39. 

Menispermuin,  44. 

Parsley  family,  82. 

Milfoil,  119. 

Parsnip,  83. 

Judas  tree,  68. 

Milk  vetch,  68. 

Partridge  berry,  111. 

Juglandaceae,  27. 

Milkweed,  92. 

Pastinaca,  83. 

Juglans,  27. 

Milkweed  family,  91. 

Peach,  57,  58. 

Juneberry,  63,  64. 

Mint  family,  99. 

Pear,  63. 

Juniper,  14. 

Mitchella,  111. 

Pecan  nut,  28. 

Juniperus,  14. 

Mock  orange,  54,  55. 

Pedicularis,  105. 

Monocotyledones,  15. 

Pentstemon,  103. 

Kentucky  blue  grass,  16. 

Moon  seed,  44. 

Peppergrass,  48,  49. 

Kentucky  coffee  tree,  69. 

Morning  glory,  93. 

Pepperwort,  48,  51. 

Key  to  families,  7-11. 

Morning  glory  family,  92. 

Persimmon,  90. 

Kinnikinnik,  86. 

Morus,  34. 

Peucedanum,  84. 

Moss  pink,  95. 

Philadelphus,  54,  55. 

Labiate,  99. 

Mouse-ear  cress,  49. 

Phlox,  94. 

Lady's  slipper,  26,  27. 

Mouse-ear  everlasting,  118. 

Phlox  family,  94. 

Lamb-lettuce,  115. 

Mousetail,  41. 

Physoearpus,  58. 

Lamium,  100,  101. 

Mulberry,  34. 

Pignut,  28. 

Larch,  14. 

Mustard  family,  47. 

Pimpernel,  89. 

Larix,  13,  14. 

Myosurus,  41. 

Pine  family,  12. 

Larkspur,  40. 

Pine,  white,  yellow,  spruce, 

Lauraceae,  44. 

Nanny-berry,  113. 

pitch,  13. 

Leavenworthia,  51. 

Narcissus,  24. 

Pink,  37,  95. 

Leguminosae,  65. 

Nasturtium,  50. 

Pink  family,  37. 

Lentibulariacese,  105. 

Neckweed,  104. 

Pinus,  13. 

Lepidium,  48. 

Nepeta,  100. 

Plantaginaceae,  109. 

Lesquerella,  52. 

New  Jersey  tea,  76. 

Plantago,  109,  110. 

Lilac,  91. 

Nightshade,  102. 

Plantain,  109,  110. 

Liliaceae,  19. 

Nightshade  family,  101. 

Plantain  family,  109. 

Lilium,  23. 

Nine-bark,  58. 

Plantain-leaf  everlasting,  118. 

Lily,  23. 

Nothoscordum,  21. 

Pleurisy  root,  92. 

Lily  family,  19. 

Nyctaginaceae,  36. 

Plum,  57. 

Linden,  78. 

Poa,  16. 

Linden  family,  78. 

Oak,  32,  33;  diagram  of  flow- 

Podophyllum, 43. 

Lithospermum,  97. 

ers  of,  32. 

Poison  ivy,  73. 

Liverleaf,  41. 

Oak  family,  30. 

Poison  oak,  73. 

Locust,  67. 

(Enothera,  82. 

Polemoniaceae,  94. 

Lonicera,  114. 

Oleaceae,  90. 

Polygonaceae,  35. 

Lousewort,  105. 

Olive  family,  90. 

Polygonatum,  23,  24. 

Lycium,  102. 

Onagraceae,  81. 

Pomme  blanche,  66. 

Onion,  20. 

Poplar,  29. 

Madder  family,  110. 

Onosmodium,  97. 

Poppy  family,  45. 

Mallow,  78. 

Orchidacese,'26. 

Poppy  mallow,  79. 

Mallow  family,  78. 

Orchis,  27. 

Populus,  29. 

Malva,  78. 

Orchis  family,  26. 

Portulacaceae,  36. 

Malvaceae,  78. 

Orobanchaceae,  106. 

Potentilla,  60. 

Mandrake,  43. 

Osmorrhiza,  85. 

Prairie  apple,  67. 

Man-of-the-earth,  93. 

Ostrya,  31. 

Prairie  turnip,  67. 

Maple,  74. 

Oxalis,  71. 

Prickly  ash,  71. 

Marsh  cress,  50. 

Ox-eye  daisy,  119. 

Prickly  poppy,  45. 

Matrimony  vine,  102. 

Oxybaphus,  36. 

Primrose,  88. 

Mayapple,  43. 

Primula,  88. 

Mayflower,  87. 

Painted  cup,  104,  105. 

Primulaceae,  88. 

Mayweed,  119.      . 

Pansy,  81. 

Psoralea,  66. 

Meadow-grass,  16. 

Papaveraceae,  45. 

Pteridophyta,  6. 

Meadowsweet,  58. 

Papaw,  38. 

Puccoon,  97. 

126 


Introduction  to   Botany. 


Pulse  family,  65. 

Service  berry,  63,  64. 

Taraxacum,  120. 

Pyrrhopappus,  121. 

Sesame  grass,  16. 

Tare,  68. 

Pyrus,  63. 

Shad  bush,  63,  64. 

Tendriled    trumpet   creeper, 

Sheep-berry,  113. 

107. 

Queen  of  the  prairie,  58. 

Shepherd's  purse,  52. 

Texas  thistle,  102. 

Quercus,  32,  33. 

Shooting  star,  90. 

Thallophyta,  5. 

Silene,  37. 

Three-thorned  acacia,  69. 

Kanunculaceae,  38. 

Silkweed,  92. 

Thuya,  14. 

Ranunculus,  41. 

Sisymbrium,  49. 

Tilia,  78. 

Raspberry,  59. 

Sisyrinchium,  26. 

Tiliaceae,  78. 

Redbud,  68. 

Skullcap,  99,  100. 

Toothache  tree,  71. 

Redroot,  76. 

Skunk  bush,  73. 

Tooth  wort,  51. 

Rhamnaceae,  75. 

Sloe,  113. 

Tradescantia,  19. 

Rhamnus,  75,  76. 

Smilacina,  23. 

Trailing  arbutus,  87. 

Rhus,  73. 

Smilax,  20. 

Trefoil,  66. 

Ribes,  55. 

Snakeroot,  84. 

Trifolium,  66. 

Robinia,  67. 

Soapberry  family,  74. 

Trillium,  22. 

Robin's  plantain,  118. 

Solanacese,  101. 

Triosteum,  113. 

Rock  cress,  53. 

Solanum,  102. 

Tripsacum,  16,  18. 

Rosa,  62. 

Sonchus,  121. 

Troximon,  120. 

Rosaceae,    56;     diagrams    of 

Sorrel,  35. 

Trumpet  creeper  family,  107. 

flowers  of,  56. 

Sow  thistle,  121. 

Tulip,  21. 

Rose,  62. 

Spear  grass,  16. 

Tulipa,  21. 

Rubiacese,  110. 

Specularia,  116. 

Twin-berry,  111. 

Rubus,  59. 

Speedwell,  104. 

Typha,  15. 

Rue  family,  71. 

Spermatophyta,  6,  12. 

Typhaceae,  15. 

Ruellia,  108,  109. 

Spiderwort,  19. 

Rumex,  35. 

Spiderwort  family,  19. 

Ulmus,  33. 

Ruta-baga,  49. 

Spiraea,  58. 

Umbellifera?,  82. 

Eutaceae,  71. 

Spreading  yellow  cress,  50. 

Umbrella-wort,  36. 

Spring  beauty,  36. 

ITrticaceae,  33. 

Sage,  101. 

Spurge,  72,  73. 

Utricularia,  106. 

Salicaceae,  29. 

Spurge  family,  72. 

Salix,  29,  30. 

Squaw  root,  107. 

Vaccinium,  87,  88. 

Salvia,  101. 

Squaw  weed,  120. 

Valeriana,  114. 

Sambucus,  112. 

Stag-bush,  113. 

Valerianacea?,  114. 

Sandalwood  family,  34. 

Staphylea,  74. 

Valerianella,  115. 

Sand-bur,  102. 

Starfoil,  89. 

Valerian  family,  114. 

Sanguinaria,  45,  46. 

Star  grass,  24. 

Venus's  looking-glass,  116. 

Sanicle,  84. 

Star  wort,  88. 

Verbena,  98,  99. 

Sanicula,  84. 

Strawberry,  60. 

Verbenaceae,  98. 

Santalaceae,  34. 

Stellaria,  38. 

Veronica,  104. 

Sapindaceae,  74. 

Stylophorum,  46. 

Vervain,  99. 

Sassafras,  45. 

Sumac,  73. 

Vervain  family,  98. 

Savin,  14. 

Sumac  family,  73. 

Vetch,  68. 

Saxafraga,  54. 

Swedish  turnip,  49. 

Viburnum,  112,  113. 

Saxafragaceae,  54. 

Sweet  alyssum,  54. 

Vicia,  68. 

Saxafrage,  54. 

Sweet  cicely,  85. 

Viola,  79,  80,  81. 

Saxafrage  family,  54. 

Sweet  viburnum,  113. 

Violaceae,  79. 

Schrankia,  69. 

Sweet  William,  94. 

Violet,  79,  80,  81. 

Scirpus,  17. 

Synopsis  of  main  groups  of 

Violet  family,  79. 

Scrophulariaceae,  103. 

vegetable  kingdom,  5. 

Virginia  creeper,  77. 

Scutellaria,  99. 

Syringa,  54,  55,  91. 

Vitaceas,  76. 

Sedge  family,  18. 

Vitis,  77. 

Selenia,  51. 

Tamarack,  14. 

Senecio,  119. 

Tangleberry,  87. 

Wake-robin,  22. 

Sensitive  brier,  69. 

Tansy  mustard,  49. 

Waldsteinia,  61. 

Index  to   Flora. 


127 


Walnut,  27,  28. 
Walnut  family,  2T. 
Water  birch,  31. 
Water  cress,  50. 
Waterleaf,  95,  96. 
Waterleaf  family,  95. 
Water  milfoil,  106. 
Water  willow,  109. 
White  daisy,  119. 

White  thorn,  64. 
Whitlow  grass,  53. 
Whortleberry,  87. 
Wild  hyacinth,  21. 
Wild  indigo,  65. 
Wild  liquorice,  112. 
Wild  potato  vine,  93. 
Wild  spikenard,  23. 
Willow,  29,  30. 

Willow  family,  29. 
Windflower,  40,  41. 
Wood  betony,  105. 
Woodbine,  114. 
Wood  sorrel,  71. 

Xanthoxylum,  71. 

Yarrow,  119. 
Yellow  poppy,  46. 

~~ 


THIS  BOOK  IS  DUE  ON  THE 
STAMPED  BELOW 


AN     INITIAL    FINE      OF     25     CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


OCT  28  1932 
SEP  99  1933 
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LD  21-50m-8,-32 


•   & 


